Hi T78a!
Thanks a lot for your detailed answer. This gives me a lot to think about. 
You are probably right that I should resign myself to use USD or EUR for now.
I was thinking to invest around 70% of my portfolio in diversified ETFs (using a value averaging plan over one year) and keep the rest in a free saving account in CHF for the moment (change to bonds if/when their returns become positive).
The thing I need to figure out, is how to rebalance my portfolio if stocks and bonds/cash are not in the same currency. This means that the exchange rate would be taken into account at each rebalancing. Not sure if it’s a good idea.
Is there a “standard” method in this case? Or would it be better to have everything in the same currency?
Thanks!