I deleted that answer because it doesn't answer the question. The question asks about the following:
One comment goes as far as jokingly saying "So technically, Switzerland also accidentally invaded France with a one-man army" when a soldier going home fell asleep in a train and ended up in France.
Your answer provided an example of US troops mistaking a Bulgarian factory for an airbase which they thought was part of their training exercise.
That's a different situation (the troops were already in Bulgaria) and you didn't address if it's considered an invasion.
You've since added the following line to your answer:
So showing up where they shouldn't be, even conducting hostile activities didn't result in a conflict.
I don't think that makes it an answer to the question. You're still using that one anecdote and you don't address whether it can be considered an invasion or what would have made it an invasion. The situation in the question also didn't lead to a US-Swiss conflict so you're basically adding another example to the question.
Suppose you want to know what makes it an invasion when foreign troops show up in uniform. Does your answer provide any clarity on that? I (still) think the answer is no, meaning it doesn't answer the question. And yes, non-answers may be deleted by the community.
I'm not saying that your example is unusable in addressing the question. If you can elaborate based on your example what consideration are relevant why it didn't constitute an invasion then that might extend to the different example in the question.