Liliana is very pretty. I would not prefer it shortened to
Liana, but that would be fine as a nickname. I pronounce the first syllable with a short "i" sound, as in the word "still", and I think most English speakers will automatically say it that way. The long "e" sound, as in "
Lee" is not difficult to say instead; it would just be a matter of correcting people until they get used to her name.
No idea what your style is, so just throwing out random ideas...
Liliana BlytheLiliana ConstanceLiliana DulcieLiliana EloiseLiliana FleurLiliana GeorgineLiliana Helena (he-LAY-nuh)
Liliana IreneLiliana JoyLiliana KateLiliana MaeveLiliana NoreneLiliana OlwenLiliana PrudenceLiliana RosalindLiliana SophieLiliana TessLiliana Violet/Violette
Liliana Winter or
WrenLiliana Xanthe