Pourvu qu'on soit à l'heure = Let's hope (I really hope) we arrive on time.est-ce systématiquement un soulagement, "heureusement nous sommes à l'heure".Oui.
On est tous d'accord. Pourquoi le répéter ?This phrase means "we are on time" - present tense.
Do you really find "I hope we arrive on time" ambiguous, Guillaume?Your context is not clear - "I hope we (will) arrive on time." The word "will" has been left out, which without proper context makes it unclear.