fdroidserver doesn’t yet have a gradle file parser, so fdroidserver can’t read the gradle configuration. So for including translations, fdroidserver currently just looks at the default location app/src/main/play. I don’t think we can currently support scanning the filesytem for those files, since it has to do it for thousands of apps, and fdroid update is already taking a while to run these days. Running gradle to get this info is out of the question since gradle is so ridiculously slow.
We’d love to have a gradle file parser in Python, so that fdroidserver can actually read the configuration. Then it would find the Triple-T files wherever they are configured.
Here it was mentioned that one can create the directory structure by hand, which is apparently working with fastlane structure, but not with gradle-play.
fastlane/metadata/android should work once it is in a tagged release of Nextcloud. There are a few apps using that layout, like OpenKeychain. Plus fastlane has the nice feature of automatically generating screenshots per locale, if you want to setup fastlane itself.