The type-ins don't seem consistent. Serbo-Croat works for Serbo-Croatian, Serbo-Croatian works for Serbo-Croatian, Samogitian, and Chakavian, but Croatian works for all of these and Croatian.
It's confusing that Serbo-Croat and Serbo-Croatian work for different answers since they are the same to my knowledge. Also, I don't think Samogitian shouldn't accept any of these. Chakavian should have the same type-ins as Croatian.
If we are counting sign languages. Polish Sign Language was used by Poland in 2006, Yugoslav Sign Language was used by Sebia in 2015 and French Sign Language was used by France in 2019
Why aren't Montenegrine and Bosnian given when you type Serbian, like the other varieties of Serbocroatian? Also, I think you should accept conlang or constructed language for that one Belgian entry. Or maybe make that one of the greyed out ones. Oh, and Feker Libi never participated in Eurovision, since the 2020 contest was cancelled.
I must've forgot to add the type-in for mmontenegrin/serbian and I'll add the other suggestions for the Belgian entry. 2020 entries are considered as official entries, despite having never actually participated.
Treble performed for The Netherlands in 2006 with a song in their own made up language: https://en.wikipedia.org/wiki/Treble_(musical_group)
https://en.wikipedia.org/wiki/Birth_of_a_New_Age
https://en.wikipedia.org/wiki/Sranan_Tongo
It's confusing that Serbo-Croat and Serbo-Croatian work for different answers since they are the same to my knowledge. Also, I don't think Samogitian shouldn't accept any of these. Chakavian should have the same type-ins as Croatian.