FWIW the plan is to get closer and closer to the vanilla version now (unless something changes). Solus used to carry a lot of patches customizing things, removing certain elements, etc., to turn it into a more opinionated, Solus-like experience.
The last few updates already dropped a lot of these, because the maintenance burden of this patch set became too high for little to no benefit. One of the main issues was libhandy, which was rejected outright by the previous GNOME maintainer Josh. Many GNOME packages had to carry one or more patches, or in some cases were frozen at a specific version before libhandy was implemented. After Josh left it was decided that it wasn't worth the trouble to keep this up, and to just bite the bullet and include libhandy.
Even Josh himself, when he was still part of the project, stated that he would return the GNOME edition to a more vanilla state (mainly because he was dissatisfied with the downstream-hostile way GNOME handled things).
So expect to see this trend of adopting vanilla settings and removing custom patches to continue.
Regarding your more specific question about accent colors I'd have to look into it. Not sure how and why this wouldn't match vanilla GNOME.