What has happened is the entire contents of the message directory at res_mods\0.9.6\text\lc_messages is now Polish. You can do one of 2 things, you can either delete text\lc_messages and revert back to the WG provided messages or you can install a message mod like YasenKrasen which has the whole of lc_messages as part of the install package.
I think actually doing a clean install of Aslain's pack will empty res_mods and rebuild lc_messages from the res version before applying YasenKrasen which would also bring you back.