The only forum system that does not support this feature is phpBB...
For example with smf there were already ways to do it 15 years ago.
So for some time I have been thinking of some workaround to have that feature without so much work.
I share my idea about it:
1) All urls go through append_sid(), so I think the best thing would be to massively rename the function to url_generation()
2) The $params parameter support string and array. This way the old code would still work.
3) Gradually add where the url_generation() function is used the new values of params that can be used to make our url configurable.
if I want to transform
you only need to have the name of the forum and the topic in this url_generation() calls
I think that with an approach like this you could have the feature quickly and it can be gradually improved