Talking off the top of my head but

  1. You just paste the enriched text, i.e. text with [b][\b] tags and so on, in the Language tab, only chaging the plain text. Bubble will automatically interpret the enriched formatting when substituting the AppText version.
  2. You either account for it by preparing a proper responsive behaviour of everything for slightly longer texts OR reword Spanish translations so they are shorter, even if you have to slightly change the message.