So my team has explored 7th level of Endless Paths. I had no Kana in my team so despite clearing room where his quest should end, I got nothing - I also got no experience points from activating those four elemental... things.

 

If I return to surface, take Kana Rua and go back here will I be able to finish the quest (and get exp from elemental towers) or is it lost?

Try it out and share your experience in the forum.

 

I'm also curious about this.

Me too  I'd like to know.

You won't get XP because you won't finish his quest.

 

The elemental things have nothing to do with Kana's quest. They open the door on the northeast so you can proceed to level 8.

^In my current playthrough, that door was opened by a switch without needing to do the elemental thing at all (maybe tis bugged? - I'd thought I needed to do it in my first playthrough)

correct, you can proceed without doing the elemental "puzzle".   All the puzzle seems to give is XP (?). 

 

Correct, you can return with kana and he should be able to do his quest.  It would be *best* if you had not yet opened the door where he needs to go... but even so, I think the game accepts it and proceeds as if he were there.

 

This is not a good topic for a no-spoilers section.   We have to dance around trying to answer without saying anything.

Edited June 3, 201510 yr by JONNIN

There are enemies in front of the exit to the level, including an elemental of each element. Tinkering with the blight machines in each room teleports the appropriate elemental blight into the little "prison" and they no long appear as enemies that you have to fight to leave the level. That's all those element-themed rooms do. They have nothing to do with Kana's quest.