In theory, it wouldn't actually be too difficult to make a small program to simply strip out all culture-specific localisation in the landed_titles file.Hello, two other guys and I did the Anglicized localisation files a long time ago, and Jaidal is correct that this is the main reason many realms are still in foreign language (that they are not in fact in localisation files at all, but landed_titles). This could be fixed relatively simply, and I could do it, but the problem would be every time the SWMH team change landed_titles (which would be virtually every time they update anything), they would have to do it twice in a SED! version of landed_titles. I'm not sure they would be interested in maintaining that.
I would also note that some titles that do not directly translate to King, Duke, Count, etc., such as Greek titles, I left intentionally unchanged, as this would be inaccurate.
Other things, like the Fatimids (banu Fatimiyyun) is in dynasties and would create more work for SWMH to maintain if updated.