The EASA FTL issue in relation to leave has been tested with the CAA by another airline where the same question had arisen. The definitions of this in ORO.FTL.105 are quite specific in that you can only move between conditions of acclimatisation and non-acclimatisation via a duty, which is then defined as a task that the crew member performs for the operator. You therefore cannot become non acclimatised as a result of travel around your leave under the EASA FTL scheme and so insisting on the full minimum time at base after leisure travel is not a requirement. Clearly none of this removes the individual crew member's responsibilities (ORO.FTL.115) to be adequately rested before their duty and to plan and use their rest before a duty. However, any operator seeking to impose MTB between a period of leave and your next duty is on a very sticky wicket.
Commuting covers the same, but there can be no question that some current commuting practices of which I think we've probably all seen examples over the years are pretty outrageous. I always used to suggest that if you had to explain your movements over the last 24 hours over the PA to your passengers then if you could do so without all of them wanting to get off your aircraft as a result of what you'd just told them, you were probably on the side of reasonableness. I can't imagine many passengers staying seated to fly with you if you'd just arrived four hours earlier from a commute in from the US. Your colleagues probably wouldn't be too chuffed either. The folk who turned up and demanded first rest in the bunk due to the length of their journey to work were taking the p*** out of their colleagues, I always thought.