Main reservoir pipe not present?

Main reservoirs throughout the consist have always been independent in Openbve, as if there's no MR pipe, however, recently it got me thinking, I did some research and realized there are practically no common brake systems that omit MR pipe like this, including those represented in the sim. I think it's something overlooked when transitioning to simulating actual separate cars compared to BVE4 with its "MR pressure on car 0 falls below set value => play compressor sounds, increase MR pressure" logic.

Honestly, I think brakes need more flexibility to become more customizable, but this is a topic for later

It's somewhat worse than that actually
https://github.com/leezer3/OpenBVE/blob/master/source/OpenBVE/Simulation/TrainManager/Train/BrakeSystem.cs#L25

The current code actually has no real brake pipe distribution at all & just uses dummy (averaged) values.

I don't want to know quite what assumptions the physics make either.

Yet it feels realistic and seems to work fine
Until I realised I've never seen compressors going off independently within a train irl, and then turns out it shouldn't work like this at all. For example, on ER2 (something I'm building and that'll probably be completed and released sometime soon) every car has a main reservoir, but only trailers have compressors that pressurize the MR pipe and then the reservoirs, and all compressors are controlled by a single pressure relay in leading cab. It's configured to use simple automatic air brake and even with all that imperfect air brake implementation it seems to behave realistically, though brake pipe discharge rate makes it feel like an EP brake (which exists on ER2, but similarly to BR Mk1 EMUs can be turned on/off) while EPB of this type isn't a thing in BVE yet

Your configuration has one inconvenient. OpenBVE doesn't allow you to have electric brake together with automatic air brake, and you will not hear any motor sound while braking. This often prevents me from using this (more realistic) type of air brake.