OK here is my advice. As a newb do not rely on a temp gauge. It is a useful tuning tool but do not follow it blindly. People have been tuning nitro engines for years without temp gauges. As you become more experienced they will become useful but IMO a temp gauge for a beginner can be misleading.
At least for now do not worry about people telling you your engine is shot. Deciding to replace an engine because its hard to tune (especially considering this guy is new to nitro!!) should be considered and absolute last resort. It’s easy to tell someone that they need a new engine when it does not cost you personally anything.
90% of engine running tuning probs can be fixed with the needles.
First things first, richen the HSN. It will not cost you anything and will tell you what’s going on with your engine.