In reply to Guido.

@Guido I totally understand your concerncs. The Polyglots team is working on improvements how to reduce waiting strings. One goal of the third Global WordPress Translation Day is the onboarding of new project translation editors which are translation contributors with rights to review and approve waiting strings.

In your case I recommend to get in touch with the GTEs of the locales with waiting strings. Every locale team has mostly it's own approval process. You'll find more information, how to contact them on the Polyglots Handbook: https://make.wordpress.org/polyglots/handbook/about/teams/