A singular “text”[1] is a distinct body of characters.
“Site text” is the agglomeration of all characters on the site.
“Site texts” are multiple distinct bodies of characters, specifically in this case being each individual overrideable body of text (i.e. translation strings).
Depending on your intent, one might want to click on “Site text” to customise the text in the site or “Site texts” to customise translation strings. This difference of internal intent is likely the cause of strife here.
Given that the destination of the link takes one to a place that allows the admin to override individual distinct bodies of text, I agree the plural here is correct.
the Christian mythos has the Bible which contains “Letters from the Apostles”… it would be reasonable to call them “Texts from the Apostles” as well
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