I have two concerns, both stylistic, the first regarding syntactical clarity, and the second regarding usage.
1) While the sentence is grammatically correct, it is unnecessarily unclear. The writer means, "[S]he left this world with zero regrets on time [she had] spent, places [she had] been, or people she [had] loved in her 29 years." You can see from the bracketed elisions of the past perfect helping verbs that the construction is not parallel. Technically, the last "she" in the series should be omitted to preserve the parallel structure; or the complete construction "she had" should be included in all three instances of the series, which would not only preserve parallelism, but also be clearer. No double-take trying to figure out what's what in the sentence.
2) Perhaps this is only a regional or dialectical peeve, but I'm pretty sure "with zero regrets on" should be "with zero regrets for."
PS I think the suggestion to add "been to" is awful. Not only does it end a clause with a preposition (which doesn't really bother me, but it's supposed to), but it's just not necessary. "Places she had been" is as clear as "Places she had been to," although the meaning is a little different. The former suggests places she "had been implanted" (even temporarily), whereas "been to" suggests ones she "had visited" (surely temporarily).
My two cents (or perhaps ten).