Partially hydrogenated oils do not exist in nature

"Partially hydrogenated" describes what we did to the oil, so of course you won't get that without human involvement. Partially saturated oils, however, even ones with trans bonds, do exist in nature. For example, raw canola oil is around 0.5% trans fat.

That aside, I'm still not sure your classification for "processed" or "natural" makes sense. The key step in partial hydrogenation is mixing hydrogen with the oil, [1] while a step in canola refining is mixing hexane with the oil. [2] How does your naturalness heuristic tell us one is ok and one not?

[1] Which makes it surprising that this would create trans double bonds, since the effect is to reduce the number of double bonds. The problem is that with all that hydrogen available some bonds flip from cis to trans.

[2] As you alluded to by saying "processed chemically".