Terrible is open to discussion, aesthetics is an interesting topic. But it is surely distinctive, and distinctive is success because no matter how badly someone spells it, the other person understands and replies
yes, this is my number for the payment, or
sorry, no.
I don't care if I spell it properly, but once I said Twint in Deutsch speaking Wallis and they understood me, payment made, mission accomplished. For internet shopping, I see TWINT more as a logo than letters from the alphabet trying to form a word.
So, is there something to consider beyond practicality for a payment system? Beauty?