Unable to answer "What are the opening hours here?" – Wissenschaftsstadt Darmstadt (Employment Agency) – way/106873868 via StreetComplete 60.0:

This building houses Ukrainian refugees, there are no signs of it being a Arbeisamt office any longer.

Unable to answer "What diameter is specified on the sign for this fire hydrant?" – Pillar Fire Hydrant – node/11829033010 via StreetComplete 60.0:

Not sure which number to put as diameter

Attached photo(s):
https://streetcomplete.app/p/256146.jpg
https://streetcomplete.app/p/256147.jpg