I agree with your cons, but the pros outweigh all of them IMO.
On the seeing backstage areas, I do think this was an oversight (whether due to lack of time/funding to fully complete thematic pieces, but I hope it's an issue they are looking to solve over time. (I think a strobe light or fog effect will be fine enough, kind of like Tiana's final lift hill effect).
Out of all the effects, the "bride on a stick" is one I'm not a fan of and hope they can add some sort of fog effect to hide it's visibility.
The finale issue I 100% agree on. It abruptly ends in a rough matter, even with the finale Drac working.
On the climbing upstairs to go down to the catacombs, this is a "suspension of disbelief" moment that we theme park fans need to lighten up on. There are practical elements we fans have to assume can't happen. Maybe they could have created an elaborate preshow to lower us down visually (but physically up - reverse of Haunted Mansion) to move guests to the 2nd floor, but I think that's an unnecessary issue.