I think you should have dedicated a bit more on Fireborn. In particular on why to not use it. I'm probably preaching to the choir talking to you, but I'm sure there's some people who will read this and then improve their game (at least I hope so).

Outside of Nightfalls and (maybe) HM Raids as a safety net, (plus solo play, but there no one cares) only bad players ever use Fireborn. The reason being that death isn't such a big deal anywhere else that the costs of a single death outweigh the benefits of people actually using their super (ideally combined with Song of Flame and HotPF) to deal massive damage (as you outlined above, massive) and generate a bunch of Orbs (one can pretty easily hit the cap of 8 before the super is halfway used up). Actually using Radiance regularly can literally take off minutes of a Strike or mission. (When you're with an actual fireteam and using voice chat, tell them to get close to get Song of Flame when you use Radiance).

"But I need FB in case I die" people say. Spoiler: As mentioned above, one person dead is no drama if they dealt enough damage, as by using their super frequently and getting up a bunch of Orbs. Plus, an even better protip: Don't fucking die. Sure, there's the occasional bug/glitch/lag or unforeseen circumstance, but very much most of the time, if you die, it's your own damn fault, and thus could have been avoided if you had been a better player. No other class as res, and yet they get by just as well, if not better. So lay off that crutch, and step up your game a bit, you will be a way better asset to your team.

I play a lot of playlist Strikes and stuff, and the difference clearly shows in the post-game reports: Me (using Voidbro or SoF Sunbro) usually leading in Kills (and Orbs picked up, if there were enough available). Fireborn Sunsinger: Last in Kills and hardly (if any) Orbs picked up. Plus it's way more fun to actually use your signature abilities than to sit on them the entire game.

I hope someone learned something from this. If I come off as ranting, it's only because I am that annoyed by people I play with doing it wrong and dragging the entire team down with them. But Whatever. Praise the Sun. (and the Void too)