I do not know if the solutions I listed below are open source ; however as an open source contributor I am used to work with some tools depending to choice of the projects:
About credits, I don’t think these tools exposes in some automated way the contributors identities. However, nothing prevents you to use these web UI tools to find who contributed and list people for example in your CONTRIBUTORS files. Another way could be to edit the automated commits these tools submit to your Git repos by adding credits to the translators (with for example Co-authored-by field).
Anticipate technical debt and follow what Google recommends. In few words, use Kotlin and Compose.
However you should really have a look on Google guidelines. In more worlds: