★ I tend to make mini cupcakes as they are easier to share at large events like hanami and people are more likely to try an "exotic" cupcake flavor if they don't have to commit to a full size one, but you can always make these in a normal size cupcake pan as well. You will just get less cupcakes (likely about 12). You may also need to bake a little longer (15-20 min or so).
★ I bought the sakura liqueur I used from
this Rakuten Ichiba seller here in Japan, but I admit I am not sure where one can procure it overseas. I would imagine some other variety of cherry liqueur might be alright, albeit a little different. Otherwise, you could just and just go for a champagne purist cupcake and use ½ cup (100 ml) of pink champagne in the pastry cream instead .
★ If you have leftover pastry cream you can store it in the fridge for a few days. I have also had pretty good luck freezing it, but from what I have read online the texture of pastry cream has gone funny on other people when they froze it so proceed at your own risk.