I have been wanting to do something similar but with 50% wheat. I have used 1 tsp of coriander in 5 gallon batches of wheat beers with good success however this was prepackaged ground coriander not freshly crushed.
Doesn’t look too bad at all to me. I recently brewed one for the brew pub where I work on the side and used around 37% wheat in the mash and added some flaked oats and rye to round the brew out. In the end it turned out great. Coriander is a great idea and it’s best to go light if you decide to use it. Maybe a quarter tsp since it’s quite potent.
Ended up going with 21lb 2-row, 5 lb malted wheat, and 4 lb flaked wheat. With the Kolsch yeast and flaked it should be pretty hazy. I may throw in 1/2 lb rice hulls for sparge insurance.