I think I'd tackle the issue by defining a variable for the term.
I forgot to mention that I use RoboHelp 9. And as far as I understand, this version does not support user defined variables in topic titles...
Ahhh, you are correct. I believe it was Version 10 introduced that.
So here's what I'd suggest. Even though you are unable to use a variable in a Topic Title, it can still be used in other places such as the TOC, the Index and in the Topic content. So I'd still recommend that you declare and use a variable for those items. Just to simplify things.
As for any topics that have the term in the title, you could create two topics. One with the term one way and the other with the term the opposite way. Then use a Conditional Build Tag to exclude and remove the one that shouldn't be found.
This may cause you a bit of a maintenance issue by having the same topic content in more than one place. (one for each topic)
So to overcome that, you would be able to add the main body information to a topic and use an Inline Frame in the two topics that would then simply be shells with appropriate Topic Titles. Either that or declare a snippet and use the snippet in both topics. Put the main part in the snippet.