Are these actually different tracks/files/whatever on whichever medium you are referencing (CD I assume from your link)?
Then you can number them 8.1, 8.2, etc. I think track numbers do not have a specified format, and that’s why we can use vinyl numbers like A1, B3, and so on. For tracks on a real honest-to-god physical CD, this would be quite confusing for people playing them on standard CD players.
If these four pieces are parts of the same track on the CD (or whatever), then they should be delmited by a slash. I think something like
Rhythmes Espagnoles: Nr. 2 Tientos / Nr. 4 Calesera / Nr. 6 Solea / Nr. 7 Paseo
is appropriate. You lose the information about individual timings, these could be put into an annotation of the recording.
You could even keep both options, the less appropriate one in a pseudo-release...