Some ISA translatable messages have backslashes in the end. It's a pretty typical Gettext issue :)
Here's a list of messages with backslashes that I could find:
- https://translatewiki.net/w/i.php?title=Special:Translations&message=Wikimedia%3AIsa-045398-Campaign+-+%5C%2Fhe
- https://translatewiki.net/w/i.php?title=Special:Translations&message=Wikimedia%3AIsa-3b3828-You+cannot+update+this+campaig%2Fhe
- https://translatewiki.net/w/i.php?title=Special:Translations&message=Wikimedia%3AIsa-b96849-Number+of+editors+that+have+co%2Fhe
- https://translatewiki.net/w/i.php?title=Special:Translations&message=Wikimedia%3AIsa-9d66ab-How+are+we+going+to+do+that+%3F%2Fhe
- https://translatewiki.net/w/i.php?title=Special:Translations&message=Wikimedia%3AIsa-ae2f78-In+the+long+run%2C+the+intent+be%2Fhe