Should I invest or should I wait while having foreign currency?

Fundamentally here you're asking for a sound prediction on direction of currency markets (and in a secondary respect the direction of the stock market). No one credible who even vaguely knows this will tell you, so you're not going to get an accurate answer to the specific question from anyone who isn't an idiot or a fraud.

Outside of this point, you clearly have some potential risk here you might want to hedge, and with these types of problems you always basically get to the same dilemma: pay an extra premium to hedge via stuff like currency hedged funds or futures with their slightly higher fees, or just take on the risk yourself for free. You can't have both.

As a result, most of this question comes down to just how much you care if currency continues to swing against you (and of course it can easily swing heavily back in your favour). If you care a lot and are happy to pay a premium to reduce your risk there are a variety of options open to you depending on your exact aims, if not you should just proceed as normal.