The documented parameters $3 to $6 (for timestamps and formatted datetime of versions) are not accepted in translated messages by the Translate UI validator, because they are not part of the English source message.
They could be "masqued" in English by embedding them in a dummy parser function call, like `{{PLURAL:$3|}}{{GRAMMAR:$4|}}{{GRAMMAR:$5|}}{{GRAMMAR:$6|}}`, however their effective values are not numbers, so `PLURAL:` would reject them (as well the `GENDER:` function call is not well suitable as a dummy function call as it attempts to perform lookup of user pages and it is costly: these dummy parameters are not necessarily a user name; `GRAMMAR:` is also problematic as its first parameter should be a grammatical case selector and not arbitrary values, and grammar lookups may also be quite intensive on resources; we just need to have these parameters silently ignored/discarded by the Mediawiki parser, without any extra cost).
An alternative would be to use another parser function like `{{UNUSED:$3$4$5$6}}`, usable in Engllish or in any translation to mark variables that were considered, but not used (and that could then be automatically removed from messages imported to wikis: all its parameters will be ignored/discarded).
Or possibly:
* `{{UNUSEDIF:$1|$3$4$5$6}}` to say that the listed parameters are discarded only if $1 is not used. And possibly a reverse condition:
* `{{REQUIREDIF:$1|at $3}}` to say that the parameters are required only if $1 is used outside of parameters iof this function (note here that $3 is not discarded, it is part if the actual message, only the condition on $1 is informative "metadata" to instruct the validator).
Basically these would be recognized by the Translation UI (to instruct messages as "metadata", but do not require these to be actual parserfunction calls, as they would be automatically discarded when exported to another wiki (or if generating translated pages in cache with the Translate UI used to translate individual units of a source translatable page; these would just be present in translation units).
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**Message URL**: https://translatewiki.net/w/i.php?title=Special:Translate&showMessage=revertpage&group=core&language=qqq
**Message URL**: https://translatewiki.net/w/i.php?title=Special:Translate&showMessage=revertpage-none&group=core&language=qqq
**Message URL**: https://translatewiki.net/w/i.php?title=Special:Translate&showMessage=revertpage-nouser&group=core&language=qqq