Maintain a wiki, no. Create an alternate frontend for marxists.org that looks like a wiki and a script to reformat the data, yes.

Don't know how much effort it would take, but they're good at releasing their data in multiple formats, so it may be as easy as just slapping on some CSS. I'd have to take a look

Honestly marxists.org should be formatted as a wiki.

I'd be willing to make this if we could host it