I think you need to determine and articulate one key point of your strategy. Is it (a) or (b):
a) You basically want to engage in currency speculation or "currency diversification" if you like that phrase better. You feel sure that the dollar will weaken again as it did from 2002-2008. Although these are "bond" funds, you are perfectly aware that they will not behave like domestic bond funds. You are happy with volatility that is much higher than is normally expected in the "bond" portion of your portfolio. And the only reason why you want an international bond fund--rather than instead of holding foreign currency directly, e.g. in various international currency ETFs--is that you want some bond interest icing on your currency cake.
b) You want a plain-vanilla, boring old bond fund that, in the long run, doesn't behave very differently from a domestic, dollar-denominated bond fund, either in volatility or return--but gives you some global diversification with respect to interest rates.
You need to understand whether the bond funds you're considering are hedged or unhedged.
If it is (a) you want an unhedged fund. If it is (b) then you need either a fund that is U.S.-currency-hedged, or one that invests in dollar-denominated foreign bonds. Vanguard announced that it was going to introduce such funds, but has not yet done so.
Annual income twenty pounds, annual expenditure nineteen nineteen and six, result happiness; Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery.