Coincidentally, when I regained administrator access on Escargot Spaces, I also nicked the infamous dashboard bug. i knew it was a plugin conflict (technically more of a plugin incompatibility with Wordpress), but from looking at the error logs to identify the supposed plugin, I network disabled it and logged in on my non-admin account to access the dashboard from there. My experiment was a success!
The plugin I disabled (Limit Blogs per User) wasn’t crucial to Escargot Spaces, anyway, so I’m not that bothered.
Now I can get to my other plans with Spaces.