Unfortunately there is nothing to share with you regarding those two devotees (Jnanasindhu Tirtha and Dayanidhi Tirtha) other than the fact that Jnanasindu was trained by Tikacarya Jaya Tirtha, and Dayanidhu was trained by Jnanasindu. "The servant of Dayanidhi was Vidyanidhi (Vidyadiraj Tirtha)"(Srila Bhaktisiddhanta Saraswati Thakur, Guru Parampara Song, verse3.)

Sripad Vidyadhiraja Tirtha was born in 1269 AD (1190 Sakabja Era)(A.C.Bhaktivedanta Swami Prabhupad. Sri Caitanya Caritamrta. Madhya-lila 9:245. purport - Bombay Gazzette.) and some say that he lived to 1412 AD (143 years). BNK Sharma alots him the time of residence on the Pitha as being 1388-1412., (page 451.) according to the Madhwa lineage he too was the immediate disciple of Jaya Tirtha and successor to the 'Pitha'. Previously his name was Krsnabhatta, (though the "Guru-acarya" gives him the name Nrsimha Shastri hailing from Badaganaadu Karnataka group of South India, and was admitted into the order of sannyas "the fourth order" directly from the brahmachari ashram and that he was very learned in the 'shastras'.)(BNK Sharma. 1961. History of the school of Dvaita Vedanta and its literature. page 451.) It is understood that he was a lifelong 'brahmacari', but for his time spent on the Vedanta Pitha is not clearly established. The times of office in the Mutt records range from three years, nine months and thirteen days; to four years; and lastly sixty four years, but for reasons best known to itself the Mutt is silent on clearing up this matter.
 The 'Guru-acarya' listings assign Vidyanidhi Tirtha a period of seven years, nine months and thirteen days as the next pontiff on the Vedanta Pitha.
 It seems that he would have been about forty years of age when he was ordanined by Jaya Tirtha, which was about one year before Jaya Tirtha's demise.  Some say he was born in 1388, but this then makes it imposible for him to take initiation from Jaya Tirtha, given that the dates we have for Jaya Tirtha are accurate.

The only written works accredited to him was a commentary on the Bhagavad Gita, and a commentary on Vishnusahasranama, which incidently was the first recorded Dvaita commentary upon it.(B.N.K. Sharma. 1961. History of the Dvaita School of Vedanta. page 453.).

In the Madhwa Mutts (Uttarradhi mutt) there is an air of vagueness and uncertainty of dates, and even sometimes the lineage. B.N.K. Sharma doesn't really have much time for the Gaudiya line in general, and gives it little credition on anything, such is the nature of academic scholars. The devotional writer Srila Kavikarnapur's "Sri Gaura-Ganoddesa Dipika", (Text 22.) mentions, "Aksobhya's disciple was Jaya Tirtha. Jaya Tirtha's disciple was Jnanasindhu. Jnanasindhu's disciple was Mahanidhi. Mahanidhi's disciple was Vidyanidhi. Vidyanidhi's disciple was Rajendra ...." However, in Srila Bhaktisiddhanta Saraswati's song "Guru Parampara" he says, "... Madhava Tirtha accepted the great paramahamsa Aksobhya Tirtha as his disciple. The principle disciple of Aksobhya Tirtha was known as Jaya Tirtha. Jaya Tirtha's service was for his disciple Jnanasindhu. Dayanidhi received the science of devotional service from Jnanasindhu and the servant of Dayanidhi was Vidyanidhi (Vidyadhiraja Tirtha). Rajendra became the disciple of Vidyadhiraja Tirtha."

Srila Bhaktisiddhanta Saraswati Thakura accepts the version of Kavikarnapur's "Gaura-Ganoddesa Dipika" and they both say that Madhava Tirtha has taken Aksobhya Tirtha as his disciple. However, the Madhwas' say that Aksobhya Tirtha was the direct disciple of Sripad Madhwacarya - this is stated in the "Guru-acarya" listings. In the Madhwa Vijay also, this is recorded, in the incident of Sripad Madhwacarya calling eight of his 'sannyasa' disciples around him at Kanya Tirtha during the Caturmasya. In Narayana Panditacarya's commentary on his own book, Madhwa Vijay, entitled "Bhava Prakashika," also says how Madhwa called his disciples in pairs, and the fourth pair was Rama Tirtha of Kaniyur Mutt and Aksobhya Tirtha of Pejawar Mutt. These incidents are also included in the "Sampradaya Paddhati" of Hrsikesa Tirtha, who is described as the foremost dear disciple of Sripad Madhwacarya.

The descendants of Madhwa are more strictly followers of a 'diksa' line, whereas both Srila Kavikarnapur and Srila Bhaktisiddhanta Sarasvati lean more towards 'siksa' lines, though still accepting both on their own validity and functional merit. Seeing that Madhava Tirtha ('Dwija' as he was known), was a forerunner and senior disciple to Aksobhya Tirtha's sitting on the Vedanta Pitha, certainly he may have given some useful instruction to the next in line. In the same way, Jaya Tirtha certainly had many disciples, and because his direct disciple Vidyadhiraja Tirtha  was the next to accept office at the Pitha, it doesn't necessarily mean other disciples of Jaya Tirtha, such as Jnanasindhu Tirtha and Daya (Maha) nidhi Tirtha didn't also give their worthy assistance. We have also experienced directly that sometimes, by the mercy of the Lord an older, more senior godbrother may take you under his wing and assist you with the development of your devotional attitude and understanding of the philosophy, and practical application of the principles of devotional service, therefore sometimes we view him also as our 'guru'.
 This principle we explained earlier through the words of Srila A.C. Bhaktivedanta Swami in his letter to Kirtananda das (29th January 1969) in relation to Arjuna being accepted in the line of disciplic succession.

Actually, Vaisnavas are always grateful for their many 'siksa gurus'. For even my lowly self certainly, as I have collected this information, everyone has stressed this same system following Sripad Madhwacarya's disciples, and this 'siksa parampara'.
 In the humble attempt to compile this work I have accepted many as my instructing gurus and I am very grateful to them for their advice, information and guidence, otherwise how could the 'sampradaya' be revealed. I do not, of my own accord, know anything about Vaisnavism, or the Supreme Personality of Godhead, Lord Sri Krsna. However, by the mercy of the Vaisnavas, and of my 'diksa' and 'siksa gurus', we are making a honest attempt at shedding some light on this subject.

There is no mistaking the fact that he was extremely well recognised for his dynamic preaching, ".....his career of ceaseless disputation with Advaitins is specially mentioned in the Charamasloka, and he is the author of at least three learned works His literacy and other activities must, therefore, have taken more of his time than barely thre or four years as Pontiff. The Guru-acaryaa also refers to his having ordained his first disciple Rajendra Tirtha 'after many years'."(BNK Sharma. 1961. History of the school of Dvaita Vedanta and its literature. pages 451-452.)

The Mutt listings are it seems reliable only as regards the cyclic years of the demise of a particular pontiff. Although there is even room for doubt in regards to a few there too! The cyclic year of Sripad Vidyadhiraja's demise is given as Angirasa which would correspond to 1392 A.D.