Could an astronomical process create elements in the islands of stability? I was reading about heavy elements recently, and I took note of the theorized islands of stability, and how some the elements involved are considerably heavier than anything we've been able to synthesize so far. Is there any known astronomical process that could create elements well above the 120-proton mark?
To this point, this is purely theoretical.  We have no solid evidence of islands of stability.  They may or may not exist to begin with.  It's hard to speculate on the methods of creating something we don't even know exists.

That said, currently, the heaviest elements found in nature appear to be synthesized in the mergers of neutron stars.  It might be possible that a similar process could create even heavier elements.  It's possible that some of the discovered transuranic elements we've discovered might be formed in such mergers, however their half-lives are so short that they break down before they're detectable.  If there are stable transuranic elements, then they might be formed in this manner, but we've never seen any evidence of them.  Me might not know what to look for, but so far we've detected no suggestions of such elements.

Another option is the accretion disks of black holes.  It is believed that nucleosynthesis occurs in accretion disks, and one could speculate that there may be conditions in accretion disks that could make it possible.

But without any evidence of the islands of instability, this is entirely conjecture.