This is an old question, but I have issues with playing the tr's in Bach's wtc. His autograph instruction for embellishments (he gave to his son) indicated a trillo to be played without the ending mordent. In his fugue 7 (d minor) he uses the tr's for notes, and then be uses a trillo und mordent somewhere else. Does he mean the tr's to be played like the trillo he described without the ending mordent?
Several of the Alfred Masterwork Editions of Bach's piano music have excellent explanations of many of these matters and even have them notated above each symbol: WTC Book 1