I've done a bunch of cleric lives lately and just finished a morninglord on my main last week. I built it mostly for casting while leveling, and even though it was mostly caster-geared in legendary, did fine healing in r10 for all of my first-time bonuses. I would still do some casting in high reaper, especially soundburst/greater command, but every time I focused too much on offensive casting, I paid less attention to hit points of party members, so deaths happened.
Starting stats: dex and str are doing nothing for you, I'd go 8 str 8 dex 14 con 14int 18wis 14cha. That said, I am an unrepentent fan of having lots of skill points: spellcraft, umd, heal, maybe concentration, 1 tumble, extra to jump/swim/whatever.
Domain: I've tried Sun domain, didn't like it, and I don't think you're invested enough into light casting for Sun to be worthwhile (eg, you have empower healing instead of empower, no caster t5 or capstone, etc). Luck domain gives +2 to all DCs, which is pretty unbeatable, since that frees up two feats on a generalist cleric. With Luck domain, turn undead adds +10 to saves for people nearby as well, which is a nice perk compared to the rest of the domains, as is displacement.
Feats: I'd suggest not taking extra turning as a feat. With minimal Charisma investment in build points and just a minor investment in gear and enhancements/destinies, I still had something like 23 turns at cap. Basically any other feat at 12 will be better. I took empower instead of empower healing, because it applies to more spells. That said, I do prefer empower heal on dedicated healers, and I can live without empower. Other than the enhancements or destinies for free/cheaper/better empower healing, there are not many spells/SLAs where empower healing makes a difference compared to regular empower. I'm not sold on SF:evo and GSF:evo together with your enhancements. DCs tend to be an all-or-nothing kind of thing, so one or two evo DC is pointless since you're not going for a caster capstone or caster tier 5. I'd swap in 2-3 shield mastery instead of 2 evocation and extra turning. The shield mastery hit points are a nice buffer in reaper as are the shield's contribution to defenses, especially if you lack reaper points. I don't recall all of my epic feats, and don't seem to have kept any notes, but they were vaguely similar to yours. Reapers have terribad fort saves - I think I was able to even stun a few reapers in r10 Night Falls on Stormreach on a healbot alt 17/3, con build with no spell focus feats and a pitiful 65 DC.
Enhancements: any cleric can heal well in r5 with zero points in Radiant. I'd put at least 41 into Divine Disciple and only go as far into Radiant as mighty turning and intense healing, maybe incredible healing. I'd need an entire toolbar to fit all the turn-based divine healing junk in Radiant Servant. When I run reaper, I'm healing reactively - left hand constantly hitting F1-F6 to target players, and key healing spells on 1 through 5. The Radiant icons all look the same to me, and my playstyle doesn't mesh with rarely-used, indistinct, and limited-charge abilities. I prefer to manage one blue bar instead of a bunch of charges and long cooldown abilities.
Turning: With the Hallowed Gauntlets as a swap item, I think I eliminated two undead per turn in r10. I managed to lead the kill count in r10 Stone Crypt Chronicle once, which was funny based on how much better than me the other players were in that group. I also died a few times in other quests trying to get close enough to mobs to turn them.
Destinies: I'm a big fan of Primal, mostly for Evergreen. It lets me stop worrying about spell points, meta everything, and just manage cooldowns. Divine Crusader doesn't add much imho and I'd go primal for a caster instead - you're not specced tanky enough to stand around in consecration. Exalted Angel is good to have to switch to the aura for the rare occasions you need more healing than you get in Primal. If you struggle in r5, the third core in Unyielding Sentinel is quite nice for knockdown immunity when wearing a shield. Renewal is still good to toss onto a tank or someone kiting a doom, although it was better before the nerf.
Gear: you have armor, cloak, wrist open, which would allow the Sharn Flamecleansed Fury set. Four fey winter items is nice to have for survivability. I struggle to use more than two pieces of feywild autumn gear on a wisdom-based divine caster, since it has no wisdom or insightful wisdom. You have collective sight, but the new goggles from Army of Eternal Night are really really nice, and might also free up your boot slot. Each of my four capped clerics/fvs have different gearsets, ranging from mostly sharn to mostly IoD, and mixed caster/healer to pure healbot for the 17/3 characters, so I'd try to build a gearset using the planner on netlify starting with items you already have, to minimize farming.
