You can add it as a new web resource via Resources > Add web resource... .
Just paste the following address: https://www.deepl.com/translator in the first "Internet address:" field.
Then, after creating a new resource, you can activate Edit > Copy source segments to clipboard and paste each new segment into the source area of the DeepL. Select the DeepL's translation (or a part of it) in its target language editor to transfer it fast to CafeTran's target language editor.
You can expect a better integration in the future when they make it available via the API.
IK: You can expect a better integration in the future
I hope so. I get a complete mess:
What's more, if I paste the source segment in DeepL, it also gets pasted in the TL in CT.
That's probably related to a certain Java 8 bug on Mac OS which they is say to fix in Java 9, officially released in September if there is no delay.
IK: ...Java 8 bug on Mac OS
Bad luck. Thanks anyway.
Works with Windows 10, thanks.