英文とのリンクを削除しました。
[#466236] All of us went except for him.
[#466241] All of us, except him, went.

@CK
"彼のほかに私たち皆が行った" means "He and all of us went."

I think this Tanaka Corpus sentence pair has created a bit of a mess.

The Japanese is presumably a translation from the English, but the English sentence ("All of us went besides him") is awkward and ambiguous. Although the basic meaning of "besides" is "in addition to", most people would read it as "All of us went except for him".

The translations into other languages (with the exception of Japanese) appear to be based on this interpretation as well.

The "in addition to" interpretation doesn't feel right because "all of us" would ordinarily already include "him". It's more natural to say something like "All of us went, including him".

I think it might be best to delete the English sentence and change the Japanese to "彼以外に私たち皆が行った" (or whatever sounds most natural).

@JimBreen, could I also hear your thoughts on this?

We all went with him. ?
probably he asked to check out a new place, and we (as a group) decided to follow him and check out that new place, too

Yes, a mess. Maybe just changing the English to "We all went as well as him" would be best, but as you say the other languages seem to derive from the other interpretation. I'll add that as an alternative, and maybe someone can unlink the other.