As I'm not able to properly merge translations back to Rosetta, the pressure for changing translation system was bigger and I finally managed to install Pootle on my server and make it work according to my needs.
So since now, then only right translation system for Wammu is available at https://l10n.cihar.com. You can find some instructions about translating Wammu at improve pages.
In order to improve translations, new system will be managed - each translation will have administrator(s) who will be responsible for content and will approve translations.
