I ran into this issue when designing an onboarding screen. I have the headline centered and the [NEXT] button as well. When there are two (or one) lines of text I prefer them centered as the overall alignment looks more balanced. When there three or more lines of text the sentences may look like an accordion in some languages and I really dislike justifying texts. Even if I try to match the length of the different text paragraphs for each screen I'll still run into this issue when translating them.
Is this a bad way of doing it (cause I'd prefer not having "always center" or "always left align") or is it acceptable in your eyes?