Why would warna-warna be wrong here? Is it unnatural to put color in plural here or is it just an option that wasn't added yet?
This is just a guess, but perhaps because we are explicitly giving all the colours we like, the pluralised word form is not needed? The context becomes obvious with the number of objects given.
Often, it's unnecessary to give an explicitly plural form of something in Indonesia.
Normally warna itself already means colours. So it is unnecessary to put warna-warna.
There is another adjective: Warna-warni (Colourful).
Is warna-warna not acceptable here?
You could also say "Saya menyukai warna hijau dan kuning" in order to be more formal, but "Saya suka warna hijau dan kuning" is perfectly acceptable for informal, daily use.
Why is "Aku suka warna-warna hijau dan kuning" wrong?