I am happy to receive feedback as I had only a handful displays and TVs to test with here. I'd say the chosen mode is negotiated properly about 90-95% of times (sometimes subsampling or range ends up being something other than what is reported for various reasons), other times the process ends up switching to some other mode - but some working mode seems to be almost always negotiated eventually, so there is no risk of getting no image - at least that was my experience so far.
The feature is not relying on existing methods (EDID override or changing framebuffer properties) but uses various undocumented APIs. Some of the seemingly relevant APIs are private and cannot be used but some other parts (luckily enough) are left accessible. I am not sure how practical it would be to make the method open source at this time as I don't know whether leaving the door half-open is intentional or not (if you are interested, I can share it with you in private, just contact me on the Discord channel).
Choosing connection details like this would be great to have as a standard feature of macOS (in System Settings/Displays, in an advanced section), Apple surely has its reasons why this is not the case. Providing this feature both via UI and CLI for free in the app will hopefully contribute to making these options taken for granted in the future for macOS users.
Note: this does not work on Intel, only on Apple Silicon. Ventura 13.2 or newer is required for the BetterDisplay 3.x version with this feature to run.