Translate strip placeholder

I need to translate the control strip into my language (Spanish).

I contacted the strip and they answered me:

Hello,

Thank you for writing! We fully understand that offering our Dashboard and Checkout in different language variations is what really matters to our users. We're working right now to get this ready for life, but unfortunately I don't have a rollout date for it, although we'll be sure to jump into it when we have an update.

So I thought I could replace the placeholder text with javascript but doesn't work with validation (form appears in popup)

https://stripe.com/docs/checkout

Any idea?