Can I try to summarise the effect of this set up, as I understand it, with apologies in advance if I am misinterpreting. You are effectively improving the accuracy of TRVs. If the room gets hotter than the rest, the TRVs will be instructed by the wall stat to shut. If the room gets colder than the rest, there is nothing you can do until the boiler kicks in again.
As a corollary, I am guessing that you don't have a central room stat that controls the boiler (because if you do, then once this shuts, there may be rooms that just get colder); the heating is "always" on; and the by-pass radiator is "always" on as well? Doesn't this short-cycle after a point, or waste heat on the by-pass?
(Or that there is a consistently colder room and that's where you have got it, but that's not what we are discussing in the first paragraph above.)
I thought this is no longer the case with modern boilers that have internal by-pass, but may be wrong.
But that's not what I meant. I meant that one should not have TRVs in a room with a wall thermostat.
I believe I read this in Honeywell docs as well when I installed my CM907.