When clicking "add" to add a new statement the initial suggestions do not use language fallbacks. The fallbacks are only done after you start typing something. They should also be done for the initial suggestions.
|Open||None||T124286 [Epic] Wikidata language support|
|Open||None||T76216 [Epic] Language fallback|
|Resolved||Lydia_Pintscher||T112112 [Task] Make PropertySuggester use language fallback|
It would be good to find an example to reproduce this problem. I cannot reproduce it with the ones from the merged tasks. Perhaps it was recently fixed with T272712: property selector fallback is not falling back from language variant to major language.