Are the schematics tier 4 regardless of the level your character was when you acquired them?
And TEWR, I meant to ask -- are you on PC or console? Sorry you're having so much trouble. =/
PC. This is actually the first time I've played Inquisition in some time. Well, this past week was, as I had started with some of my other characters that are canon to my multi-verse (as good a name as any for it). One of my 3 Adaars, a bit of Vaida Cadash, some more of Marisa Lavellan, etc.
Try loading a previous save; had one auto-save while Cassandra was in free fall, and had to do this myself.
Wardens are mentioned in dialogue, but am guessing that the DLC was written w/o the choices from the Vanilla game as Descent can be played at any time.
Nah it kept crashing for any save, at least on Nasir. Tried both autosaves and the manual one before them and it didn't work. Considering my laptop had an auto-shutdown last night I figure it may have been a heat issue. I'll try again when I get home from work.
And yeah, they are mentioned, but it's a rather casual thing. I mean, it wouldn't have taken all that much tbh. Just a mention of "The Wardens are with the Inquisition" and seeing them at the various camps as just standing NPCs would've made enough of a difference to me (though I headcanon this DLC as going in tune with the Warden-arc a bit).
But more on that later, maybe.