The biggest problem I have seen with many true venturie motors sealing..ST RJ PA  Thunder Tiger  Magnum etc is that a large percentage of people that take them apart , put the spray bar and venturie back in the engine an cause a problem that they are unaware of and swear didn't happen.
I have seen this on many dozens of Motors, They will nick off a tiny piece of debris when pressing the spraybar back into the case  (the threads of the bar will cut off tiny specs of ventuire case..whatever) or they will have tiny pieces of silicone..clear that they cannot see of colored that they just ignore. ALL OF THESE PIECES OF DEBRIS Will make a leak at the side of the case ,by getting trapped between the nut and the case side, or the other end of the bar and the case, or it will get lodged in the feed hole.
Or the tubing they inserted will be loose and move back and forth.

The delrin seal on a PA spraybar is a seal or gasket, they will, just like any other gasket have to be replaced if taken apart a lot. The PA spray bar is made so you can take the whole thing out...without...taking the needle out constantly. You do not have to take the needle out at all or even move the setting that the needle is at to remove the entire assembly.
I have 7 motors in my shop at this exact time that have dings on the O-ring venturie seat where people have used a metal object to try to force the venturie out ...instead of grabbing the sides of the venturie. This too is a big cause of leaks along with damaging the O-rings and reusing the damaged O-ring.
Or not cleaning the silicone bits that are stuck and smeared all over the inside and outside of the Venturie hole in the case.

There is nothing wrong with sealing any engine venturie/case seal, just do so in a neat clean manner that doesn't cause you problems later.
Also whenever you install "any" Spraybar in "any" engine ,after you insert the spraybar take a stiff fine brush, or a stiff toothbrush and brush the threads clean, and brush the sides of the case clean

No motor that I have ever used has had silicone sealing the Spraybar, not in my Vectra, Intrepid, or KATANA, none of them leaked or surged. The PA 51 in my KATANA is steady as a rock and needles perfect, as does the 75 in my CF ship, as does the 40 in my Vectra.

Do not hesitate to do whatever you need to to get any problem fixed on whatever your running..be it ,using silicone to seal up the venturie\case\spraybar, or replacing seals gaskets or O-rings that need to be replaced.

Regards
Randy