Having recently embarked on painting old spindles on the 100 year old stairs leading up to my newly renovated master bedroom (and wanting the new and old to blend seamlessly) I can offer you some product advice that worked for me.
Some of the spindles has a high gloss lacquer, some had several layers of high gloss paint, and the associated chips. Like you I wanted a smooth finish, and to maintain (what was left of) the details of the spindles. I did the work myself on weekends so sanding/removing (lead-based for sure) paint was not an undertaking I had the patience, time, nor tools/resources for. So, I opted to de-gloss the existing surfaces (I used Krud Kutter), then I filled the worst chips with either wood filler or putty (whatever you’d use on a painted wall) depending on if it was a painted or lacquered spindle, then I used Stix primer, followed by a satin finish top coat. I used a foam roller to get a nice smooth finish. For both the primer and the paint.
I believe that the stix primer will prevent any orange from bleeding through, and does a great job of adhering to tough to paint surfaces, so even if the de-glosser doesn’t get to every nook and cranny, you should still get a long lasting, durable base coat for your paint to stick to. My stairs get a lot of use with 6 people (4 kids) going up and down all day, getting banged by toys, laundry baskets, furniture, etc and I have had zero paint chips, bubbles, smudges, peeling, or bleed-thru. It’s been a year. I also used stix on all my previously lacquered doors and none of them are having any issues at all, even though they have the added challenge of being in a bathroom with constant exposure to heat and humidity.
I would hope that your contractor makes the situation right for you. None of this should be outside his/her capability, as I’m just a homeowner, not a pro, and I did not find any of this challenging whatsoever.
Btw-I’m not affiliated with any of these products. Just a regular ol’ consumer.