You have the concept right. However, in Spanish the 'r' in "Pedro" is not a trill but a tap. In Spanish, the trill only comes after /n/, /l/, or /s/ or at the b

You have the concept right. However, in Spanish the 'r' in "Pedro" is not a trill but a tap. In Spanish, the trill only comes after /n/, /l/, or /s/ or at the beginning of a word.