I would not view this as “foreign currency trading”. One way to think of it is hedging your dollar value risk. If, say, half of your consumption is of goods from overseas, then you ought to hold half of your investments in non dollar denominated assets. If the value of the dollar declines, your the purchasing power of each investment dollar will decline, but the overall amount will increase. If the dollar increases, the investment total will decrease, but the purchasing power will rise.
One problem with the ETFs is that they take fees. You can actually buy international bonds and CDs directly. I am not clear on what the fees are for doing that, and have been trying to find out via Schwab.