Typography: font subsets?

I must have gone through 20+ useless themes until I found Verbosa. It is beautiful and perfectly suited for my site (basically, song lyrics that I write). The typography options are great, but there is one major issue: there seems to be no way to specify font subsets. Without that, the theme is only usable for English content, as special characters do not display properly in other languages. (The browser displays these characters using its default font, which looks ugly, or just shows garbage characters instead.)

Google Fonts supports font subsets, but there seems to be no way to specify a subset in Verbosa. Ideally, there could be a drop-down box to select a subset, but I could just as well use the “or enter google font” box for that. The problem is that the “or enter google font” area doesn’t seem to allow that. It would look like this:

Merriweather:300,400,700&subset=latin-ext

However, this doesn’t work at all. It seems to produce some css error, as the font for the entire site reverts to the browser default (not the specified google font). The setting only works without the “&subset=latin-ext” spec.

Is there anything I can do to specify the required subset (for all Verbosa font options)?