You're welcome! And with regards to the timer thing, I never meant to say it's too easy! :P Just that it needs an additional incentive to go against the brain's natural laziness.
Also I forgot to mention this last time but I found it really offputting that the visible part of the piano keys on each cards stops at B. I'm used to see things going from C to the next C. The additional "missing" black note helps my brain locate the notes more easily.
Also as an improvement and a somewhat different challenge, what about a version with just the note names themselves, not the visual representation? :)
Take care!