So... I tried what you guys suggested as soon as I saw your answers. Here are mines ^^
Like I said, maybe poorly, the glitch doesn't occur when I manually load (F2) the default position after I loaded a custom one, everything works fine.
It happens only when I do that through [ANIMTOOLS_IdidntEvenKnowIcouldBeFuckedLikeThat] (that's a joke, I have no such file named like this lol), and only with some animtools positions, not all of them.
Before I ask for help, I tried many changes in the animtool position settings, even in the animtools mod settings, unsuccessfully.
I used a minimal dialog to debug it, and the switching back to an oral position (default one in my case) after some positions (the previous one was a doggy one, but some other doggy do not trigger the issue) was just enough to make that glitch occur.
The [DEEPTHROAT] trigger didn't change anything, I tried with lowest values for intro resistance and throat resistance with no difference. By the way I never noticed any impact on using [DEEPTHROAT] generaly speaking, I'm not sure I really understood how it really works, or it just doesn't work for me, that's odd.
Howerver, changing the dick size like you suggested DrZombi worked just fine ! I ran several tests and so far moving the [ANIMTOOL_] trigger didn't really made any difference, but I don't mind writing 2 more lines to use the dick size workarround, I'll manage to include it in some settings lines where it won't add any waiting time.
I didn't looked further, so I can't tell if an interraction with another mod would explain the issue, but I'll probably check it later cause I'd really like to know where could it come from.
I encountered all of this writing a funny story were a secretary gets the very spanking that you Sligerbult inspired me
(that's just the start)
I wonder if the result won't trigger more laugh than anything else hahaha
Anyway, if ever the result is satisfying enough, I might translate it and share it with you guys.
Thank you for your swift and efficient help ! And don't hesitate if I can ever help back, I'm not too unexperienced either