This isn't a real issue, it's for a pin when people come inevitably crying to me about these versions not existing.

ProjectE has officially skipped 1.17, and will almost certainly not make an official 1.13 release.
The reasons being:

• 1.17: Official Notice From Devs - "This is an all around unstable and incomplete version of the game, it has been skipped in favor of 1.18."
• 1.13: The ProjectE developers have noted that 1.13 is unstable and does not have a release build, and it seems unlikely that they will make a release for it.