fwiw, I made a CD with CD Text in Toast and get basically the same thing: if any of the Performer fields are left empty when entering the text in Toast, the empty Performer fields are shown with an added blank space when the CD is imported on Mac command line (drutil cdtext), or when imported in Wavelab.
The only difference is the added blank spaces are always there with the Toast CD, even if all Performer fields (album and tracks) are left empty when entering in Toast. (Unlike Wavelab, where if all album and track performers are left empty, blank spaces would not occur on CD import).
It doesn’t look right, and seems like an oversight, but it does appear that Toast does the same thing. (at least my old version of Toast).