No - Buddleia should be cut half-back at this time of year - to avoid wind rock - then hard back in the spring.

Kerria is pruned differently. It's best to do it after it flowers, then take out some of the older stems from the base - maybe up to a third, looking for any dead ones first of course. You may find some dead tips later in the year - I just snip these off to tidy it up.

Yes, don't cut the Kerria yet or you will cut off all next Spring's flowers. It won't grow anymore this year anyway, so unless it is in the way, leave it til after flowering.