Can't select XFrom after-post-page that's not in site's default language

Steps to reproduce

Steps to Reproduce:
1. Use AlloyTech site with English and Swedish enabled

2. English as default language.

3. Move to Swedish site and create a contact page, contact Block and a thank you page . All in swedish

4. In Contact block, select/create a form and try to select a thank-you page created in number 3 (swedish).

Actual: You can't select a Swedish page.

Expected: You should be able to select a Swedish page since you are in Swedish context.

NOTE:

This bug requires a partial fix in core (#118178)