This is kind of a basis question, but do we really know for sure the enemies and items/equipment in the paintings are imaginary and/or originated from them? We know the equipment Jonathan and Charlotte find in the paintings can be used in the "real world". Brauner can also travel between the paintings and reality. So taking that idea further, wouldn't that mean he could create anything he wants and then take it out of the painting? Like, if he imagined "invincibility armor", "the infinity + 1 sword", and "the instant win" spell, he could put these items in a painting and them take them out? Personally, I think it would be less complex if Brauner only created the environment of these paintings, and he uses Dracula's magic to place monsters there as guards. That's how I always perceived it at least.
In fact I agree with this. I agreed with this long ago - he's manipulating the castle, so it kind of follows that he'd place Dracula's minions inside these paintings to guard them. I also agree with the logic for the spells and overall items that can help the heroes because, if I were Brauner, I'd not intentionally place things that can help vampire hunters defeat me inside my paintings. This specially goes for Sanctuary, a spell that represents an
incredible threat to his plans, too.
And then we get to the conundrum: So, hypothetically speaking, Brauner did not place these items there. He merely created the worlds and placed Dracula's guards there. But Sanctuary did not exist before in the real world, or it'd be largelly known as an effective purification spell that cures vampirism.
How then did it appear inside the painting? Who invented it?
My point about the monsters being independent from the castle, however, says more about Brauner's inspiration and abilitites than what I truly believe about it.
Could they be Dracula's minions? Yes, and I do believe this to be the case. BUT could Brauner have painted them with basis on monsters from reality? YES TOO. Hell, we see Brauner fabricate monsters en masse in REAL TIME in seconds, of course he can do it! Saying that "No, Brauner can't take inspiration from reality to paint monsters using his creativity" is too much naivette.
Now, I'll not be dishonest: Brauner-made monsters look a lot more abstract and nightmarish than the other monsters, which is why I believe the other monsters not directly seen-to-be-made by Brauner are actually Dracula's minions. But when you get to the core of the logic, monsters are monsters and Brauner is able to paint them. End of story. Death Mask, for instance, looks like something Brauner did. Brauner may be a surrealist, but he still knows how to paint things pretty close to the real counterparts.