I noticed that the Vis Sources page of the wiki has not been updated. Crawfs and I had some suggestions: https://forum.atlas-games.com/t/gof-magical-obj-penetration/218/1
Additional comments are welcome.
Here are some ideas for the remaining sources:
Rego: During the highest tide in the spring, a jellyfish swarm can be found quite close to shore, and two of these creatures contain 2 pawns each of Rego vis. Swarms have been sighted during other high tides, but the vis is only present during the highest tide. Of course, care must be taken in harvesting the jellyfish, as their sting can cause a painful rash that lasts for several hours.
Terram: At some point during the year, a severe thunderstorm rolls through the coast, and lightning strikes a nearby sandy beach. The resulting "glass" contains four pawns of Terram vis.
I think that covers the needed vis sources?