When checking a 3.6 dev local site with a 100% core-translated es_mx language pack, I found that the site footer has a strange mixture of some translated and some other untranslated strings in the same sentence.
I described it and added images in https://docs.moodle.org/dev/Translation_FAQ#If_you_think_that_you_have_found_a_hard-coded_English_language_string_different_from_the_above_ones
It seems that the AMOS language string 3.6dev | pageinfodebugsummary | core_admin
This page is: {$a}
is indeed properly translated at the beginning of the sentence (first green rectangle), but the {$a} part is a mixture of some translated and some unstranlated components .
?