I recently noticed that the default signature on Commons includes localized text for the talk page link, e.g. [[User:CalendulaAsteraceae|CalendulaAsteraceae]] ([[User talk:CalendulaAsteraceae|<span class="signature-talk">{{int:Talkpagelinktext}}</span>]]), which I think is a great feature for a multilingual wiki.
Based on this discussion, it looks like this has been the case since 2021, and, as was brought up at the time, the fact that all parser functions in signatures are automatically SUBSTed means users cannot both customize their signatures and have their talk page link localized.
For example, I would like my signature to also include a link to my contributions page, like so: —[[User:CalendulaAsteraceae|CalendulaAsteraceae]] ([[User talk:CalendulaAsteraceae|<span class="signature-talk">{{int:talkpagelinktext}}</span>]] • [[Special:Contributions/CalendulaAsteraceae|{{int:contribslink}}]]), and the automatic substitution means that the text of my signature is only available in English: —[[User:CalendulaAsteraceae|CalendulaAsteraceae]] ([[User talk:CalendulaAsteraceae|<span class="signature-talk">talk</span>]] • [[Special:Contributions/CalendulaAsteraceae|contribs]]).
I completely agree that i18n must not be an afterthought, and if the software itself is interfering with localization, that's a problem. How feasible would it be to add an exception for localized text to the automatic SUBSTing of parser functions, and what is the appropriate way to propose this?