While trying to run your tool under wine emulation in Linux, I get the following error message (I'm using DeepL with an pay-as-you-go API key):
An error has occured: Bad request, message: 'formality' is not supported for a given 'target_lang'
I tried translating this game:
https://f95zone.to/threads/translat...nster-amirin-rj295122-head-shop-kasai.156936/
but I'm working with an actual full version directly from dlsite. It appears to be a DeepL error message, c.f.
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It claims to have successfully translated 4 other files, before glitching out on the CommonEvents.json. I grepped this file for 'formality,' but did not find it. The 'translated data' directory was made, but it is empty. DeepL API usage tab shows no usage yet, but I'm not sure how often that gets updated.