I don't know why they can't do it call of duty and Minecraft have cross play with Xbox and Nintendo and PlayStation just add it more people play on console then pcIt is unlikely for this to ever happen, unfortunately. None of them allow their devices to connect to other networks other than their native Xbox Live, PlayStation Network and Nintendo Network. So connecting to a pc running a TerrariaServer will probably never be possible. Microsoft did try to bring Xbox Live connectivity to the Nintendo Switch (through the game Cuphead I think, can't really remember) but seems to have gotten the cold shoulder from Nintendo. There are an SDK available for some other platforms such as pc and Android though.
Edit: By the way, is there a list available somewhere of the bugs that have been fixed?