Sorry to hear of your experiences with regulators, both fixed and moveable, they shouldn't do that. I design process control analysers and instrumentation systems, so I have some experience of petrochemical refining, and maybe this will help:
Butane and propane are distillation products from crude oil, sometimes from natural gas, sometimes from the further processing of heavier boiling streams.
Butane and propane are the names of pure compounds, but what goes into a gas bottle is the natural mixture of gases that all boil at a similar temperature, but they will all be gases at room temperature.
The key point being that the what goes in the gas bottle has to have been a gas at close to room temperature, and unless there was prior contamination of the gas bottle, heavy components like waxes and oils won't make it into the supply stream.
It is not uncommon for machining oil or other lubricants used in machining aluminium components to be inadvertently included in new regulators, or tubing fittings, whatever.
It's easy to tell the source of the contamination, a simple laboratory test is required, but this can't be judged by eyeball.
From the Eriba owners groups - there have been no reported regulator problems - but the Eriba uses the German GOK wall mounted regulator.