That doesn’t even necessarily have anything to do with sync, though. That’s wanting to bypass changing pitch range settings and having to utilize soft takeover, which could occur in a variety of settings. You’re actually using sync right now to partially bypass them, but that doesn’t entirely solve it, as you’ve figured out.
The problem with what you’re asking for is that while you imply you don’t like soft takeover slowing you down, what you’re trying to do by bypassing it will actually cause it to occur more often. Soft takeover will switch on on the master layer if you’re doing your relative fader thing on the opposing slave layer on the same deck. Soft takeover will also potentially switch on whenever you hit the shift button for any other function other than your virtual relative pitch fader changing thing. You hold shift to clear a cue or loop and it’s going to potentially register a fine wobble increment on the pitch fader and switch all the fader positions on that deck to soft takeover… necessitating even more bypassing of it with your feature.
If Layer A is the master, Layer B is the slave, and you want to suddenly bring Layer B’s fader way down and then have all the other decks and layers follow its fader, you should be able to hit Sync first on Layer B, then Master on Layer B, and move its fader, even if that means you have to move to some soft takeover location first before actually changing the speed. Range will adjust automatically to accommodate the on screen pitch state when soft takeover lights. Master lights for the entire deck on both layers, but your soft takeover lights (that don’t go away even when you move to it) tell you which of the layers on that deck is not the master. You need that master lit on both layers in order to know which deck has the master on it. They could always add on on-screen master/slave indicator in future firmwares, though.
Set Pitch Range to the Pitch Bend buttons directly instead of requiring shift. It’s under Preferences/Utility. That will be easier to switch Pitch Range when you’re trying to manually move any layer or deck to a wider pitch fader position than currently possible. You already hit Sync. If you hit + instead of Sync, you could actually get to 100 BPM using just the fader and without even having to hit Sync then Master.
If you’re using sync a lot and especially if you’re toggling master around and don’t want to manually adjust the fader, you will also need to go into Utility/Preferences and allow sync toggling without shift. That’s actually the only way to easily toggle sync on and off quickly and reassigning master at-will.