Note that _group_ and _subdir_ ...

without the / that is actually the separator.

Please, keep the previous

_account_`:`_project_`:`_tagname_`:`_group_`/`_subdir_

or if you prefer

`_account_:_project_:_tagname_:_group_/_subdir_`

It is more accurate, the : and / are not parts that need to be replaced.

None of those formats render correctly in the final HTML result.
The first (original) one comes out as

account`:`project`:`tagname`:`group`/subdir

and the alternative comes out as

`account:_project_:_tagname_:_group_/subdir

which is why I changed it in the first place. Both of the above outputs are pasted from the generated HTML.
Having twiddled a bit, it seems I can use double tics and have it render somewhat along the lines of how it should be.
This:

``_account_``:``_project_``:``_tagname_``:``_group_``/``_subdir_``

gets rendered without any control characters slipping through, and the separators do stand out.

Thanks, fixed.