From the xscreensaver 5.31 changelog:
UTF-8 text support (instead of only Latin1) and antialiased text on X11 with Xft (instead of only on OSX/iOS) in fontglide, noseguy, fliptext, starwars, and winduprobot. The other text-displaying hacks (apple2, phosphor, xmatrix, and gltext) also now accept UTF-8 input, though they convert it to Latin1 or ASCII.
From the xscreensaver 5.31 changelog:
UTF-8 text support (instead of only Latin1) and antialiased text on X11 with Xft (instead of only on OSX/iOS) in fontglide, noseguy, fliptext, starwars, and winduprobot. The other text-displaying hacks (apple2, phosphor, xmatrix, and gltext) also now accept UTF-8 input, though they convert it to Latin1 or ASCII.
Fixed in xenial and later.