It's fine, but I really doubt your intensity if you're saying you can do RDLs to failure lol. Do you mean 0RIR?

Upper / Lower / Push / Pull

An upper lower would still do fine. 3 uppers and 1 or 2 lower days. The problem with it though is elbows get trained a lot more and that's usually not good for them unless you're young or really durable.

Chest + arms, back + legs?

You need a bit more pulling lifts and you can also do mass day on strength day. Just doing strength work first and mass second. Spread it out a little more between both upper days to balance it out. I personally like to cap my lifting days to 8 excercises but that's me, you could try that. Also embrace supersets where they pair well. For instance doing a DB Bench and a DB Bent Over Row as a superset or DB Curls and DB Triceps and so on. Will save time, add cardio and just make it more interesting. Also probably move the ab training to the lower days to help balance things more.

There's almost no back/pulling exercises in that

I'd add another row & a pull down or pull up

If you care more for strength try a strength focused sub. My advice will be for muscle growth. Your split can work, albeit frequency is low, so train those sets super hard, probably with myo or rest pause as well here and there. Consider a upper lower as well. With one lower day and two different upper days. That could work well too. Or you could lift every other day, alternating between one upper and one lower. With supersets your upper day would likely be 45 minutes though. As for strength I have no advice but for size you can get away with pretty much all machines to save further time on setups.

I wouldn't be running a split if I were concerned about keep as much muscle mass as possible while staying efficient with my time.

I would go incredibly simple: 1 pull exercise, 1 push exercise, 1 leg exercise every session. You could even use 5/3/1 programming for the first lift of the session, and supersetting would be easy. So for instance:

Day 1:

• Bench press
• Lunge
• Row/pullup

Day 2:

• Squat
• Pullup/row
• Incline press

Day 3:

• Deadlift
• OHP
• Row/pullup

You could play around with exercises depending on which muscles you consider more important, but this would be time-efficient for maintaining with decent frequency.

Muscle growth requires a surplus of energy which at your weight your body would obtain the surplus from your fat stores. So you'll grow muscle fine until you're too lean. Than you'd need to switch to a bulk.

Is 200lbs with lots of muscles or just average built?

if average built, you can run deficit higher as chances of muscle loss are low, so you can start at 500kcal deficit.

If you've lot of muscle, it makes sense to lower your deficit and lose the fat over long term and you'll not lose much muscle.

am I going to build any muscle at all?

muscle gain rate drops with increasing deficit. So, it depends on a) how much muscle you already have b) how much deficit you running.

For example, if you are an average sedentary person, you will build decent muscle while going down in weights.

1400 might be a bit steep, but you're looking at a 12+ month diet, likely with multiple breaks, so the number you start with doesn't matter too much. you'll have to adjust along the way regardless of what number you start with. that being said, every day, eating your goal weight in grams of protein + some fish oil + some veggies will cover your absolute needs. everything above and beyond that depends on your daily activity and how much of a deficit you want to create for that day.

you'll very likely build some muscle on the way down, but it's not really the point of a fat loss phase and it's not something to put too much focus into. you have the flexibility to train with intensities and volumes that will stimulate that growth - but you then have to prioritize recovery from that training stimulus (generally eating more resulting in a less steep deficit and longer diet). or you can just train with half the volume (as you're not going to grow much muscle, even if you do build some), and instead use that time for cardio, increasing the deficit resulting in a shorter diet.