I am not going to comment on the structure of the files, but crtystaltile2 can extract them out. as to whether there is further compression I trust ct2 in this when it says (0) at least on the first DE 0000.p file.
If you are just trying a language patch I'd just do a direct replace the en ones with language of choice. if your language of choice isn't in there, well at least you have plenty of files to check and compare against to help build your own script inserter.
Albeit the menu stuff might be a little different to handle graphic-ly. Isn't there an eu coming out?
Since I didn't quite answer the question - Anybody with "pascal source code" experience able to answer the question?
sorry, if i wasn't that much help.