I didnt say you have to use iron/bronze fodders for lvl beyond 50 you know =P but was looking at 60+ at least for the plats tenhou mentioned.

@exkidd: Karma should get a few more levels mainly with exp armor + fairy if possible, due to the need for her to get some attack stats to deal more dmg before her skill ends.

Saki has high UP cost, but she does better ranged dmg than Horace. still, Horace, usually suffices for your ranged unit in a melee slot role. (saki just for instant skill on deploy since you already got her to lvl 20+ anyway)
As for duelist, with lilia and kerry around, what you need next is a hp soaker, which is basically Cellia here (unless you have conrad or lyla. but you can double cellia as preparation for AW as what tenhou mentioned). Horace, in general, is more of a ranged unit in a melee slot more so than duelist (but she is helpful for thinning out waves or dueling some minibosses at her spot) (I tend to clump duelist and ganker together more. Ganker = deploy to block unit btw. Duelist is simply a unit that can fight 1v1 against tough units)

and I repeat, Bernice and Bashira are great to level and to have around, even if you already have better. still, from your current lineup, they are lower in priority. Because of that, I am suggesting units that are geared more towards what seems to be your weaker areas.
as for Uzume, she is most certainly better than Sakuya, but to my understanding, advance guards and samurai in general don't get good chances to shine. Still, Uzume is great after AW.
as for Lynn/Ada, reason I didnt mention them is due to having Cypria, which should suffice for most situations, and considering your lack of CR for those 2, cypria is likely a better option. Rikka is a niche unit, that can be used as a single-use bomb (IMO) - deploy her among a large crowd of weak units, then when her hp is low, activate skill and watch her deal as much dmg as she can before pulling her out. her high base stats make her a decent hp soak, but she cannot be healed. hence the single-use bomb comment. Rowanna also a niche unit in a certain sense, as a great duelist that can self-heal for maps where you can't heal e.g. Lynn's event 4th map where no ranged slots.

Just justifying my suggestions~