As for adding the water, I feel the same with my Cumin seed Leiden. It's nice to see the seeds but adding all the water made it a bit over the top..
I added the water that my cumin seeds were boiled in and it was still pretty mild. I liked it fine though.
How much cumin seed did you add per how much milk? Mine was 1TBS/4gal.
To my taste the mustard was a bit to overwhelming, next time I make it I will not add the water I used for steaming the seeds.
Sorry to hear about the excess mustard character, Herman. Part of your education, I guess. I've got a lot of that going on myself lately.