GALSWINTHE: The forst element
GAL is not clear. Most probably it's a romanised form of Germanic
GAIL* ("frisky, randy"). SWINTH is Middle High
German "swinde" or "swint" ("strong, fast").
FREDEGUND: Old High
German "fridu" ("peace", roughly) + "gund" ("fight, combat")
BRUNEHAUT: OHG "brun" ("brown", usually meaning the bear, which the Teutons didn't dare call by its "real" name for fear it might turn up) + "hadu" (?**) (same as "gund")
* This is taken from H.Kaufmann, Ergänzungsband zu E.Förstemann, Personennamen, 1967
** The hadu part is just an educated guess