I would KILL for stained trim! Instead we're stripping off 80+ yrs worth of oil paint in multiple layers. What method are you using that makes it easy? I've found it to be a major PITA no matter what chemical I use and we resorted to the very unsafe dry scraping. Stain your trim. I'd have to see the room ot get a better idea, but I can picture your pine, as that's what we have. I'd go with a stain that's fairly natural and brings out the yellow, at least for the purple room. You might want to vary it a bit for the other rooms. Ideally I'd do it all one stain and keep it consistent, but we won't be doing that because 1)we chemical-stripped the trims in one room which stained them much darker than the original, so already they'll be darker than we'd like, and 2) those walls are pale yellow and the dark works, but our bedroom, for example, is sort of a deep red copper, and a lighter trim looks better. FWIW - we have "Colonial Maple" ,Olympic 41533 against a pale yellow wall and "Natural", also Olympic in the red/copper room.

If the orbital sander is a really good one, then you shouldn't even need the belt sander. You can really do some good skid mark damage with a belt sander.

Sorry to hear your problem but I have been stripping old outside widows myself I feel the worst thing to do is sand it I never do that first dust goes everywhere plus nasty stripper I do not use aswell get a nice professional carbide paint scraper a little elbow grease and it comes off like shaving your face put a tarp down on the ground to catch all the waste do not worry about the low spot if they are smooth your painting over that anyway and the majority of clean area will adhere the paint over that now after you scrape it with a 2 inch wide carbide get a slight smaller or pointed scraper or similar sound like alot of time but it goes pretty quick with a carbide professional scrapper and they are not that expensive after you scrape lightly hand sand with 80 grit then 100 then 120 or now wipe down and paint it will be fantastis without all the dust from trying to sand it first before scraping and all that nasty stripper that you left on there will easily scrape off do not strip again safe your lungs and time and other time and lungs aswell I do it this way all the time the windows and or doors and trim go rather quickly with alot less mess and and alot less dust and fumes that go every where that you cannot control please do as I suggested safe your and others health and time! health

Most likely a false wood grain paint kit was used. First coat was maybe a tan then used a stiff brush and brushed on a darker color to make streaks. I forgot what was used over this, however, most likely it was a clear varnish. Been too many years since I used a wood grain kit. I believe regular paint stripper will work to remove the wood grain paint. Try it in a small area. Check with Home Depot or other and see if they still sell the wood grain kits, a good way to find out exactly what might be on the boards.