I had plans to use boiled linseed oil on all the wood and then using shallac as my top coat. I'll test the wood bleach and peroxide, I've not mixed the two before.IMO, the only effective method for removing deep seated oxidation and evening out color in antique SYP is to bleach with a two-part sodium hydroxide/hydrogen peroxide wood bleach followed by neutralizing with vinegar, yet it considerably lightens the wood which is kinda trendy. Oiling will darken it to a degree & somewhat restore the color.
I didn't want to but it is all off the wall and sanding is better. I like the idea of replacing the middle panel but I would need to read up on how to do that.It lacks sanding in the corners which is beyond difficult. The easiest fix would be to use a wax and grease remover to cut the wax and then stain the lighter wood to match the dark areas. Because of the door panel to achieve the lighter color I think the best bet would be to tear all of it out and remake it. You could remove the trim, sand it and re-install it but the door panel would need to be cut out and replaced. You could never adequately sand the wood in the corners.
If you have a router you could get a template guide and make a jig to route the frame out on the back side. Then remove the panel and either sand it or make a new one and install it like it was a piece of glass with trim to hold it in.I didn't want to but it is all off the wall and sanding is better. I like the idea of replacing the middle panel but I would need to read up on how to do that.
I like the no nonsense approach but I enjoy taking wood that is old, damaged, and just about trash and bringing it back to life. There is a sense of accomplishment restoring and saving antiques. Also working on a 1890s handmade buffet that was left on the side of the road with alot of damaged. I don't get into the creative aspect of wood working.It's 100 years old, so it should look like it's 100 years old. It's called character. If you made it look brand new, people would just think it's new. Like putting new parts on a Model T that's otherwise all original.
I'd just sand off the last traces of paint, make sure to get rid of the perpendicular sanding marks, then just oil and shellac it.