Capell (1963) lists this as a Wulamba (a name given to the cultural area of N.E. Arnhem Land, called Murngin by Warner) dialect. Oates and Oates (1970:224) lists Maidjara as a name only listed in AIAS files and, in her later work, Oates (1975:388) deletes it saying it is a name associated with a myth. Based on the information available, Maydyara / Maidjara is unlikely to be a language name, nor is there any linguistic data available. See also Yolngu Matha N230.
Speaker numbers were measured differently across the censuses and various other sources listed in AUSTLANG. You are encouraged to refer to the sources.
Speaker numbers for ‘NILS 2004’ and ‘2005 estimate’ come from 'Table F.3: Numbers of speakers of Australian Indigenous languages (various surveys)' in 'Appendix F NILS endangerment and absolute number results' in McConvell, Marmion and McNicol 2005, pages 198-230 (PDF, 2.5MB).