I have a site that is using WPML plugin for page translations, however it is not working quite well with Custom Permalinks. There is some kind of redirection loop or not found errors going on with the translated pages.
Both plugins are great and people choose WPML and Custom Permalinks because they work well with their individual functions, but it would be great if these two could work in harmony.
Many users have already brought this up on WPML forums and they said they would like to work with your developers if you may cooperate.
Please contact WPML using this http://wpml.org/documentation/theme-compatibility/go-global-program/
Most users would more likely to drop Custom Permalinks if they discovered it doesn't work well with WPML.