I think you should separate the venue (architectural space) and the entertainment (novelty lighting) and solve one before you move onto the other.
For example, if black is a color you are going to keep for the interior, then respect it. You have black chairs and back trusses - with white cables attached? The string lighting should have been black wires. Lose the extension cords and install permanent discreet electrical power where it is needed.
It may seem like a small thing, and by itself it would, but you are several layers deep now with a myriad of unrelated and conflicting touches. You've got a few pieces of voile on the ceiling, but it seems non-committal at best. Just master one thing at a time and stay conscious of having a coordinated design.
As for the ceiling - I do a lot of large tents, and the ceiling is the thing we have to deal with. My advice generally is that we go all or nothing. If we don't completely cover it, then we don't put anything there to draw your attention to it. If the ceiling is not attractive don't try to dress it up unless you can make it 100% something else.
The black truss and wood are amenable to something softer and more familiar - I would want to give the truss a floral solution and give the bottom rails/lights a softer more wedding appropriate feel. (I would consult someone who can help you achieve this, it takes a special kind of talent but it's worth it.) A better positioning of the chandeliers would then add a more convincing elegance.
When you think lighting start with maintaining the space design - focus on warmth, and illumination. Point sources are a secondary touch. DJ lighting is irrelevant because we are trying to book the space - not the DJ. (Deal with that later on a case-by-case basis.) Remember that every venue you have been a DJ at was first sold and booked on the basis of the room - not the DJ or band they hired. All of the photos you use to promote the space should be lit for the best room appearance NOT the entertainment. The "party" isn't the thing you should be selling because it's a given. It's location, location, location, and that holds true both indoors and out.