Hi Tony, Sorry for not checking this area out sooner. What you have done looks darn Good to me, so be proud, also you can look at the areas that didn't get covered completely, not that everything has to, as areas that were painted some time ago by the little folk and have weathered over time, so it just add some character!
I haven't done too many buildings, but do know as Chet, Garry and others have said it's tedious work especially as we get older. A Jewelers head magnifier, with glass lenses, really make viewing the work a lot easier, I use mine all the time. Also I find that by having the paint a bit on the thin side it tends to flow better to get into some of the areas. Also a bit less can be applied without getting to much extra flow but it does/has happened to me. That when some touch comes into play.
I only have one DPM building I started to build and painted the windows and doors while the walls were laying flat on the table. If your building is already built then you have a height issue to deal with and I'd suggest placing several books along side the building and about the same height to rest the edge of your hand on while doing the fine painting. Your possibly doing this as your work looks very steady to me.
With my Horseshoe Meadow Depot the window & door castings were all white metal and I used a fine tapered square jewelers file to try and clean them up from flash. I did a bit too much on a couple but those went around back where they don't show. As far as the painting I did the frames in a medium green if I remember correctly and used depot for the mullions but it got to be very tedious where the inside of the frames came down to the mullions as well as at the door inserts. It's far from perfect and I had to do some touch up here and there so don't feel like the lone stranger. I had to stop and have something to drink and get away from it for awhile. After all that was done, I used some of the glazing material from Micro-Mark to coat the back side of the windows, earlier in the year when the weather was on the cooler outside, and placed them on a 1/4" mesh screen I laided on two 1x2 boards that were on top of an oil heater set on a lower temp, to aid the glazing in drying. It requires a fair amount of this medium, indeed it seemed like it was too much which I applied with a small round stick tapered at the end, but when it dried it filled in all the openings very nicely.
But I'll have to say that the 14 windows of various sizes and the three doors plus the freight doors were quite a challenge to do even though they were separate cause I painted both front and back on all, well maybe not the freight doors.
Anyway Tony your your work is looking very good so be proud!