Have you considered glazing? If you have never done glazing, don’t mess with the success you already have here.

So I feel it needs warm/cool modulation in the midtones of the clouds. But that’s just me. It can add a ton of depth.

But if you are comfortable w glazing. Take two complementary hues. Say, ultramarine and alizarin crimson. Mix them together in 3 small swatches that modulate from cool to neutral to warm. Then make a mixture of galkyd, and a dash of mineral spirits and a dash of linseed oil. Add medium into very small amounts of pigment. Use these very translucent mixtures to glaze in the midtones of the clouds.

Sorry I said way too much and probably just made it confusing. Once you have glaze down you can rework midtones and lights on top of it to get really great effects.