umamusu-translate VS Weblate

If you wanna go the extra mile for english translations you can follow the instructions on this to have the interface, missions, and skills to be translated. Some of the story is translated, but from what I've seen it can be hit or miss, there is an option to opt out of any machine translations if you find it jarring. Using localify that comes with it also allows for unlocked fps, auto fullscreen and other stuff. The translation process can take a pretty long time since everything is in individual files it seems like.

Noccu's (use on your own risk)

For translations I can recommend you to use sites such as Crowdin, OneSky, Transifex, Weblate. Lot of smaller (singe or small team) developers are handling translations with the help of their users. You would be surprised how easy and how fast it is to manage translations at no (or nearly) cost this way. There is a lot of users willing to help to translate the app to their native languages.

weblate.org — It's free for libre projects up to 10,000 string source for the free tier, and Unlimited Self-hosted on-premises.

WebLate (their projects dashboard)

I'm using weblate.org. It's open source so it made the most sense to me to use for an open source Android app. It can also be used for free. It's not trivial to use but can be managed.

if the author of the app use a public translation service like https://weblate.org/ or https://crowdin.com/ you can do it via web browser.

For translation, using a Weblate instance makes a lot more sense over using Google Sheets https://github.com/WeblateOrg/weblate

hosted.weblate.org is only free for open-source projects, but it shouldn't be hard to find alternative hosting, or launch a Docker container in the cloud??

If there is not any, i can recommend Weblate, which is open source translation platform and hosting is free on their side for open source projects, or you can also self-host it.