A post on my phpBB forum had the following link (no additional markup):
viewtopic.php?f=1&t=1234&p=4321&hilit=foo#p4321
This link has been converted by the importer into the following markup:
[viewtopic.php?f=1&t=1234&p=4321&hilit=foo#p4321](https://example.com/forum/some-topic/1234/2&hilit=foo#p4321)
And the link target is broken. Looking at the regular expressions used for conversion, long_internal_link_regexp will only apply to complete links whereas short_internal_link_regexp doesn’t - it will happily convert the start of the link while leaving the rest of it (here &hilit=foo#p4321) unchanged.