You are overestimating the capabilities of TRG 300s. They are great but on their own aren't a game changer, at least not in the quantity we have in place. Burmese also have more potent system like SY 400/ DF-12A in their inventory.
A comparable example of their vulnerability is Russian Tornado MLRS which are also shoot and scoot system, got picked off by Ukrainian drones.
We will just have to agree to disagree on this one.
You are not comparing like with like here.
BD will always be on the defensive and Ukraine has access to far more modern systems and intelligence than Myanmar will ever have access to - USA is literally feeding them real-time AWACs and others surveillance aircraft data.
Russia has no choice but to put its MLRS out in the open as it wants to take ground from Ukraine and then Ukraine has access to real-time data from USA to pick them off using drones and HIMARS.
When you use these systems for defence purposes like BD will be doing then picking them off even for the USAF will take some time and effort. IAF and especially MAF will not be able to hit anymore than a small fraction of the 18 available in a reasonble period of time.
Yes these systems are not a true game-changer but they give an extremely powerful deterrent against India and hence the idea that India has any say in what BD buys is a non-starter.