If you're that set on a fixed lunch schedule put a calendar block for it and don't feel bad for telling people you have a conflict at that time. If they ignore/don't care about that then the real problem is shitty coworkers/company (possibly against the law depending on location), not clueless accidents.

Something I've learned with eating + time zones is "find out when people actually eat, not what time you'd be eating if your clock was changed too". Apart from cultural differences you easily conclude lunch is "sometime between 11:00 and 2:00" just by surveying ones neighbors. Add in a few hour time difference and suddenly it's impossible to schedule a meeting unless you guess, learn, or see it on their calendar when scheduling.

For people whose schedules are full, it's almost mandatory to have a calendar block for lunch. I prefer 3 PM or 11 AM lunches honestly so I'm flexi; it's when the restaurants have more capacity, unless they just ended shifts.