Thank you I could have sworn max dex affected atk as well. I must be messing up rule sets. Thank you for correcting me.

And yes wands of mage armor are amazing regardless of edition!!

Based on their stats:

Celestial armor 15 ac (8dex 6armor, light) -2 check, dex atk-1, fly 1/day, 22,400gp

3 ceremonial silk armor 13ac (9dex, 4armor, light,) no check wand of fly, 20,250gp

I would probably go with the 1atk and -2ac for cheaper. Especially if I'm wanting to fly more than once per day, if I wasn't concerned about flying sub the wind of fly with cats Grace and the silk becomes 15ac and allows atk to raise to 11. Where celestial would cap the attack at 8

If their pc wasn't pushing the limit of armor vs dex the dex cap from armor is going to start affecting their ability to hit targets, and offense tends to be just a bit better than defense in pathfinder and DND.

Idk why but I was thinking rune lords were more giants and such. But if you're using the bow then by all means keep it. I'm not familiar with the module.

Goggles of Truesight could be useful if you're running into illusions, and such. Negates anything less then 100% miss chance or concealment.

If you are good buying wands. Fly, haste, stone skin, rage, and gravity bow are all good wands for an archer.

Next part is really play dependant:
I might recommend a single level in zen archer for the 1ac(higher if Wis goes up), -1bab, 2 will, and free feat. This will depend mostly on how often you full attack and get to use manyshot. A level 17 ranger gets 2 hits on its first attack for a total of 5 hits no adjustments or 6 hits all at -2 when using rapid shot full attack. A Zen ranger would get 4 hits no adjustments 5 with -2 when using flurry full attack.

If you don't get to full attack a majority of rounds you might be better with a level dip and retrain rapid shot and manyshot. Meaning a level dip could free up three feats.