I know very little about GERMANIC styles of clothes but I do think they would assume the current fashions of the time period, especially among royalty. I do think that the writers and costume designers do follow a general time line of European clothing in order to show different times in FTL.
THE first OGRE wars seem to be dating from the Dark Ages about 1200 to 1600s . Europe was a feudal system of serf/ overloads.
Snow/ PC James/ EQ all seem to be of a much later time period similar to the 1700s. Of course there are regional differences as the costumes in Italy were different from France, different from English, different from German etc. ( Germany was not a united region at the time but rather principalities.) Each region had their own particular influences on the costumes; but I do think they reflect styles and fashions in the real world.
N.