Hello. Someone that has done ample "end game" content here. Not even close. What does Nature do after it uses Regrowth when Tank has pressure, and all of your buffs are out? This assuming the Tank isn't a wet paper sack (plenty of Tankers can't take an actual hit when streakbreaker/debuffs set in.) Empathy, and to a much lesser extent Pain, can cycle AP/HO without the need to waste resources. It also has stable single target Regeneration in AB, and can be stacked with RA assuming Tank is good and keeps pressure. If the Tank has any form of Regeneration Resistance (imagine taking Ageless Radial in this day and age) that will saturate the time between cycling AP/HO, and will also hard float in the event you have to Triage. This is all assuming the Nature is allowed to maintain proximity based on the situation. I can happily just fly out of range of everything and continuously provide strong ST healing to the Tank.
Also, I wish more people would actually play Nature. Too many lazy Healing Aura/Soft Cap/Fighting Pool clowns pick up the set and play like trash. No CM rotation, no Fort rotation, skipping Absorb Pain, skipping Adrenaline Boost; the marks of nearly every PuG/Roleplayer Empath. Hell, I've played with some that have skipped CM, for god's sake. Nature is thankfully a lazy set that encourages you to spam Regrowth and blow your massive PBAOE load. Bonus points if you beg with "Gather for X." I'm not even saying that to be discouraging. The lazier the set, the more reliably I can assume my teammate is going to take advantage of their tools.
Nice guide, but it lacks experience behind the wheel. I'd get your hours up in more difficult content, then maybe do a rewrite.