In the suggested translation "Adam himself built nothing." in English this can have both the nuance of "Adam built absolutely nothing, with or without help from others." OR "Adam may have built something, but if he did it was not by himself." Which nuance is being portrayed here in Esperanto????
To me "Adam himself built nothing" is not ambiguous. It very clearly means that he didn't actually build anything. He may have had things named after him - or may have commissioned some buildings which other people built, but he didn't build them.
If we want to say that he had help, we're more likely to say "he didn't build it by himself."
Mem is generally an emphatic particle - sort of a verbal underlining. Yes, it does have the secondary meaning "by oneself without help from others" - but it's usually clear from the context. I wouldn't understand this sentence this way. If I wanted to express the idea that Adam did build things but not by himself, I would say something like:
- Adamo konstruis nenion sola.
- Adamo konstruis nenion sen helpo.
My take is that it's not correct. "He built himself nothing" means "he built nothing for himself" which is different.