getHumanTimestamp() allegedly respects https://www.mediawiki.org/wiki/Localisation#Separate_times_from_dates_in_sentences by creating a "timestamp" which (in English) is actually an adverbial syntagma composed of a date (sometimes implied) and a time, or just a single adverb.

"just-now": "just now",
"hours-ago": "$1 {{PLURAL:$1|hour|hours}} ago",
"minutes-ago": "$1 {{PLURAL:$1|minute|minutes}} ago",
"seconds-ago": "$1 {{PLURAL:$1|second|seconds}} ago",
"monday-at": "Monday at $1",
"tuesday-at": "Tuesday at $1",
"wednesday-at": "Wednesday at $1",
"thursday-at": "Thursday at $1",
"friday-at": "Friday at $1",
"saturday-at": "Saturday at $1",
"sunday-at": "Sunday at $1",
"today-at": "$1",
"yesterday-at": "Yesterday at $1",

However, the current qqq doesn't state that this syntagma is expected to be used as lego piece in other messages. The result is in the best case an error in capitalisation, as with Italian:

"monday-at": "Lunedì alle $1",

In worst cases we'll have incorrect declension.

Solution: edit the qqq to state that the messages will be used as part of full sentences in other messages, ideally with one MediaWiki core example (and hope the translators can actually fit a correct translation in this system).