Several questions here.

1. A hero is adjacent to the smith. The OL moves the last monster from the map tile and places Valyndra on the map - can she be activated immediately?

2. Can the OL play dash on Valyndra to eat 2 weapon caches in 1 turn?

So there was a hero adjacent to Jorem but they did not free Jorem, either they failed the test or they chose to not free him to buy them some time? So now I assume it is your turn, so you move your monsters off the forge tile, creating the situation where there are no monsters on that tile and at least one hero, so Jorem is now free. That triggers Valyndra to be placed her lair. Which because it is your turn you could then activate her so place her adjacent to one weapon cache take it as your first action, then dash and take the second.

It all seems legit to me.

Yup thats pretty much what happened. Thanks for the claification.