So okay, I did some testing.
I had
https://www.opensubtitles.org/en/subtit ... olocene-en translated from English into Dutch, using AWS.
Firstly, note that this subtitle is NOT verbatim, but a 'compressed' version taking technical things into consideration, reading speed being the most important one. I chose this one, to avoid an 'unfair' bad result, which would more likely happen with a verbatim subtitle having much more text within the same period of time, and thus be already too fast to begin with. I chose AWS, because supposingly that's the better one, beating DeepL.
I expected technical flaws, mainly in this reading speed, since Dutch is on average around 20-25% 'longer' than English. And indeed, average CPS-ratio (unit for reading speed) went up from 11,9 to 15,4 CPS. That's 30%, which is a bit more than expected, but okay. Maximum reading speed however went up from 22,2 to 84,4 CPS. That is extreme, very strange and not expected at all.
So I had a look what happened.
For some reason, the translating machine merged some lines together, first time at subtitle sequence #99. After that, all translated text moved up one sequence, For example the translated text of English #101 into the Dutch #100:
101
00:10:05,689 --> 00:10:09,316
Let's go, you ready?
I'll take it easy on you.
became:
100
00:10:03,028 --> 00:10:04,311
Laten we gaan, ben je er klaar voor?
Ik zal het rustig aan doen.
So from here the subs may be well translated, but they are more than two seconds off-sync. And from here the same thing happens 8 times more, so progressively things get worse and worse. Sorry to say, but this off-sync issue makes the subs simply worthless and not usable.
Still, I had a look at the actual translation. To be honest, I expected better, but also here the result is disappointing. A fair amount is quite okay, but many sentences seem to be translated word by word, creating twisted sentences and for example a plural verb tense for a singular subject. Or some alien full stops or capitalization. And of course some very literal translations for expressions like "I'd tap that" (I would sleep with her) or "you are a tool" (something like "you are a weirdo", nothing to do with hammers and screw drivers or so), but that's normal for machine translations.
Anyway, I did the same using DeepL.
This is much better, but still, a similar thing is happening. At #810 a line gets merged and so from line #811 the subs are off-sync.
Also translation wise it's better, but still obviously machine translated.
Since this subtitle source was meant to create the best results, I didn't bother to do some testing with subs from which I think the result would probably be bad.
Sorry, but I think your service needs some fine tuning.