Alex, I like what you are doing, but these scenes you are creating have far too "fresh and new" a feel to them for what is supposed to be an old, somewhat dilapidated mansion and the surrounding grounds, buildings (mausoleums) etc. Even the cracks are beautifully drawn and well lit

/owing to a sharp contrast to the background they are placed on.
In the house, carpeting is completely out of place in the bedroom, for instance, the tile adds to the eeriness of the room, and the moonlight filtering in touches it off. Note the shininess of the tile as well. Those gas lamps are secondary lighting in there, moonlight is the feature.
You are making beautiful scenes but the world you are attempting to recreate is far more dark and foreboding than the detail, texture and brightness your scenes permit.
Look at the 'DIJON' tomb for example -- it looks like the name is a neon sign. The original coloration was similar except in its case, it was set on a pilot-blue mausoleum backdrop which absorbed some of the intensity of the yellow lettering. With grey or particularly red brick, that needs to be toned down or altered in color entirely.
The sky in the bottom-right tomb scene is beautiful, I won't criticize that at all because the liberties you've taken with it make the result so perfect... but the general atmosphere of the game is such that you won't have or shouldn't include such brightly-lit gravefaces, for example, or outdoor scenes with fully-lit fore or backgrounds.
Outlines, shadows, and dimly lit foregrounds/backgrounds are the mainstay of the graphical world this game exists in, and that is owing largely to the creative decision of Roberta Williams in how she wanted the atmosphere and environment to appear, not owing the limitations of EGA (it never stopped her before.)
Overall I think you are doing a very good job though. Intense red walls in the first room, as well, would require spotlights of 2,000+ lumens to make appear that deep a red, even if the material was colored for it (the moonlight and lamps combined couldn't cause the red to reflect that deeply or brightly.) Moonlight, and blue-light in particular, bleeds red of reflectivity, it would appear washed-out, like it does in the original game. The gas lamps are not bright enough to produce more than a slightly visibly detectable color improvement on those walls.
There is a definite LucasArts lighting/intensity surrealism present here which is not necessarily present in Sierra games -- this is more cartoonish than it is purely graphical adventure (where the emphasis of the game was literary and contextual, and not so much graphical or ambience.)
I suggest that for examples of how to light and shade the swampy outdoor areas you take a peak at the KQII remake's swamp area and the texturing of the outside of the castle, graves, the Church graveyard, and so forth.
Keep up the good work, these are just observations I've made of what you have produced so far. If your creative decision is to make a brightly-lit, fresh and new-feeling atmosphere for the game, so be it. (The couch for instance is far too plush and the wooden frame of it is too obscured -- this is antique furniture made from real wood; the couch in the first room.)
Everyone loves a comfortable-looking room, in reality or a game-world, but the less comforting it is, the more it builds towards the distinctly-uncomfortable atmoshpere of the game. It brings reality to the situation, the player shouldn't feel at ease... its a creepy old mansion that has a cast devious guests staying there... and the outside is dark, cold, foggy, swampy, and scary. Neon signs on the mausoleums, when contrasted with such flowing VGA textures otherwise, simply clash too harshly to fit the part.
Anyway don't take any of this too hard. I'm a professional critic, the decision in how you want to present the game is obviously entirely up to you. Just consider what direction you want that to be.
Cartoonish <-> Realistic (Lighting, etc)
In character <-> New/Different character (Fresh furniture, etc)
PS: And if realistic, the black outlines on everything need to be blended or highlighted with the colors of the surrounding textures, not simply remain black lines as they are.