Even with an official GApps package, Jelly Bean presents challenges:
First boot after flashing GApps can take 5-10 minutes. Android will show "Android is upgrading" and "Optimizing app X of Y". This is normal.
about Gapps or Android package management:
A quality package provides an MD5 hash (e.g., f9e5c543f8a7b1c23d4e5f6a7b8c9d0e ). You can verify it using TWRP's built-in check or PC tools like WinMD5. Corruption during download is the #1 cause of "failed to flash" errors.