To round ths topic up:
Jimmy Smith "The Singels" was released in Japan in 1983 on LP and did not get a CD release.
Yes, it's a compilation, and all titels ended up being bonus cuts on other Jimmy Smith CD's. I had to buy "Jimmy Smith at the organ" (Blue Note 1525) and "Softly as a summer breeze" (Blue Note 4200) twice because of them.
The only titel missing in my collection is the alternate take of "Plum Nellie", recorded 1957. 2. 12.
But I can't decide to buy the Mosaic-box only for one missing alternate take.