I frequently look at US charts and have trouble remembering what various signs and symbols means
You don't remember because you don't need to remember. If you got an FI job in the US, how long would it take you to get up to speed FFF? No more than a couple of days I imagine.
There are a few people (and dogs!) on this board who are very sniffy about US flying in general, without ever coming up with valid reasons why. Exposure to different flying environments would make you a better instructor IMV.
If you have the qualifications for the job, the rest comes down to your personality & character.