Internationalization -- impact on other modules?
The i18n modules can have a huge effect on a site, as they integrate with a large number of modules. Many modules for example deal with taxonomy terms and displaying them, so they all need to be compatible with i18n.

The main problem is that many content elements (like menus, taxonomies, ..) are not designed to be translatable or even just language aware. So the i18n project needs to alter a lot of things and build data structures and API's on top of those provided by core.

Also, there have been a number of API changes unfortunately, so it's possible that the modules you mentioned have a broken i18n integration due to that.

You need to provide more details on what exactly isn't working to get more help than this. You can also try to check the issue queue of the broken modules to see if there already is an issue for this and if not, open one.