Re: yellow lightning. The idea is to deplete that moment of its original meaning of tying her to Palpatine. Since the lightning represents the inner darkness she fears, building a saber with a yellow blade at the end could be seen as her having accepted and integrated this into herself, reaching a sense of balance.
Wow, I didn’t think I would be convinced of this idea so quickly. If no one tries to make this change I’ll try to help out with it.
Re: clones. Ideally somebody, anybody’s face could be shown on a small group of people in like one shot aboard the Sith Fleet ships. Obviously with what we have to work with having Temuera Morrison’s voice is about the only viable shorthand with which we can telegraph that these are clones, but it raises questions. Moreso if one is into the EU, as clones had to be phased out over time.
I think it depends on what angle you want to approach the Final Order. Are you gonna keep the Final Order as its own thing, or does the First Order just assimilate the resources of the Sith Eternal.
If the Final Order is meant to be a fully-functional military, then I think the Sith Troopers being clones would be a fun Easter egg and a simple explanation for how they built an army in secret.