"referrence pressure" is not in many users vocabulary.
Nor is "vacuum signal"
The fixes suggested for getting the pressure constant (across the topside of the regulator diaphragm) are endless and many are worthless.
The carbs on glo engines also suffer from air pressure problems .
The use of exhaust pressure to the tank can fix most of these.
Glo engines because of the fuel used ,typically can tolerate much more varience in fuel to air ratios.
My ZDZs and Evolutions etc., don't have fuel mix problems as noted -because I always center the tanks on the carb .
This keeps the fuel head at a more constant level
Also my cowlings are always setup to provide maximum air extraction at the rear or bottom of the cowl. this helps stabilize interior pressures and keeps the engines cool to boot.
For what it's worth , a large plenum attached to the top side of a Walbro type carb, will stabilize any pressure problem. a balloon on a piece of tubing attached to the diaphragm vent can do this. OR a line from the vent to a box at the carb inlet, etc., can also work