The new moulding will have to be a near perfect match otherwise it will look wrong. I did all the panels of an inner door with new mouldings and it does look really nice to have sharp profiled mouldings. Does your front doors have 6 panels or just 4? It does look great when they are all fresh and new. If you replace just one panel, it won't look right, but you could just paint several times to try and take the edge off the mouldings. I think no matter what you do, it will always look slightly different, but that might be OK?
I just repaired my front door. I call it sympathetic restoration. For my front door, if I had replaced a single panel or replaced all 6 panels, it would have ruined the character of the door. It takes 100+ years to get doors into that state, it like the patina of an old bit of wood. Even though the door would be improved, it just wouldn't look quite right again. As it is, it'a a magnificent front door.
I still have the original inner lock on my door, but only had one key, but years ago I happened to work at a place that did phosphor bronze castings, I got 2 spare keys made at the end of a production casting, which happened to be for a rather special submarine, lol
I'm normally in Hillsborough at this time of year, but not this year!!