Sorry for not doing anything for almost a week, but I was in holidays with no Internet connection (and after that I discovered Portal Prelude ).
Anyway, I finally added the fix from D'Lanor + fixed again the bug RedSoxFan had + fixed the tubes.
I think the tubes were buggy because the region were activated twice - because of the Smart Seek. Which means once the anim done Plasma runs it again... and the avatar enters again the region... etc. So I disabled it while the tube was down, and it seems to work fine.
Here are the two modified files (if it finally works fine, I'll update the other attachment for the Wall on single player Uru).
@Diafero: I hope you're not getting bored to update the files again and again .