I see one grey area that could use some clarification. Opening the save, opening a city, and looking at how alternative tile assignments would affect production and research rates seems to be different from making moves, deals, etc. and strikes me as being OK. A member might then advise in discussion that "we should work XXX kind of tiles to speed the rate at which we get YYY". Since one could calculate this by hand without changing the worked tiles on the screen, seems to me not a violation (doing easier what you already could do the hard way seems to be what the HOF mod is a lot about). But you may disagree.
If you don't want the off-turn members looking at tiles this way, then is it OK for the on-turn player to look at options, post screenshots of them, and ask the team for opinions?
dV