ah these are definitely caused by BTT's automatic variable declaration, which happens e.g. after launch. BTT takes all triggers that have a "set variable value" action assigned and makes their variables available - this is done across presets, currently even for disabled ones.
In 5.316 I have limited that to enabled presets. Also I added some logs that allow to identify which trigger was responsible (~/Library/Application Support/BetterTouchTool/Logs )
defining variable XXX from trigger YYY - parent ZZZ