Launchpad has a PO file translation website. This makes it easier for non-developpers to contribute and review translations.
https://translations.launchpad.net/
So what would it take to get Wine's PO files on Launchpad?
* Launchpad tracks who translated what string and if we choose the 'Closed' permissions model only approved translators can update the translations. So that means we should be able to get patches with full attribution. https://help.launchpad.net/Translations/YourProject/PermissionPolicies
* Launchpad would need to pull updated PO files from Wine regularly. Ideally that would be automatic and happen daily (both to account for translations happening outside Launchpad and to take changes in the resource files into account quickly). https://help.launchpad.net/Translations/YourProject/ImportingTranslations
* Conversely Launchpad should submit patches back to Wine. Ideally that would be automated as much as possible but I'm fuzzy on the details here (especially on how to preserve attribution). As for the periodicity, maybe the best would be weekly or just before Alexandre makes a release. https://help.launchpad.net/Translations/YourProject/Exports https://help.launchpad.net/Translations/YourProject/PartialPOExport