Danke dir, I suppose it's not completely wrong but "feels" wrong. The sentence using "at" came from an American native speaking person..

I don't think "native speaking person" exists, so maybe that explains the strange preposition :-)

"At" does not sound wrong to me, actually. "Participate at the conference" = "participate there", in my ears. I would definitely use "at" in a sentence like "participate as a speaker at the conference" for instance, so maybe it is a contamination from that, or maybe just linguistic slovenliness on my part. "Participate in" is certainly fine.

I normally agree with AE procrastinator, and I do agree that participate AT emphasizes "participate there", but here I strongly disagree with "participate as a speaker at the conference".

Participate at simply has a different meaning than participate in, in the same way that "an einer Konferenz teilnehmen' is different from 'auf einer Konferenz teilnehmen'. To participate in a conference is to take part in the conference as an activity -- to present or ask questions or whatever. To participate at a conference merely takes the conference as a site or location for participation in some unspecified activity, which may be related to the conference but may just as well not be. "Where will you be participating?" "At the conference."

I would hold "participate at" to be a grammatical error worthy of correction. Native speakers also make mistakes.

I think this is related to the point I am trying to make (although I am not sure, of course -- it might be that one just can't translate the distinction very well). In English, one has to create a pretty weird situation to use "participate at" -- it's not a phrasal verb like "participate in something." It literally just describes where you did the participating, not what you participated in.

"How were you able to participate in the Zoom workshop? Weren't you at a conference last weekend?"

"Yes, I participated *at* the conference. I just used the WiFi in the hotel café."

"While at the conference, I participated in a number of different panels."

"Auf der Konferenz habe ich an verschiedenen Diskussionen teilgenommen."

I definitely agree with #8 - I always find "participate" to be vague and would prefer "attend the conference or give a paper at the conference" or "actively participate in the discussions at the conference".

I also accept Lonelobo's point regarding at vs. in - I think I do use "participate" rather imprecisely. I would say "he participated as a speaker at the conference" but I think I would still say "He participated in the conference as speaker". I don't know how many people have to make a mistake before it becomes a regionalism or alternative acceptable to some speakers, but it doesn't seem to have reached that point, so I will have to watch my usage when translating.

+1 to participate not being a great verb.

Upon reflection AE procrastinator, I think that "participate as a speaker at a conference" is not bad, because of the addition of "as a speaker". I would find "participate at a conference" wrong, but "participate as a speaker at a conference", although it sounds a little ungainly, is not wrong.