What happened to the Oort Cloud? Did the two voyager probes detect it? Or has that entity been dismissed? The Oort Cloud was the only spherical structure I have heard of in this system. And a spherical particle flux of ice WOULD dampen the cosmic ray shower.
It appears to me that Sol's plasma ejected-wind, would have an hour glass pattern around our system. Disk-y. Not in any way spherical. Like a light house light beam, only particles. AND not straight flight. The plasma swirls out of our system. And that swirl of particle flux varies.
I doubt a heliosphere actually exist. If you define it with shape due to in vs out particle density, then that shape should be a constantly waving disk.
Therefore I would suggest that the galactic particle flux(cosmic ray) is rarefied. And some of it might be local.
I can find no physical process that could form a spherical heliosphere.
It's hard for me to believe the Sol can maintain a collective consistent magnetic field.
But I am only comparing articles and narratives, not making measurements.
It would take many probes just too get a small clue.