This is the 13465th most frequent German word.
bestehend
"Existing" or "current".
Here, 'bestehend' functions as an adjective, meaning 'existing' or 'currently present', describing the building.
Das bestehende Gebäude wird renoviert.
The existing building is being renovated.
In this sentence, 'bestehend' is used as an adjective qualifying 'rules', referring to the rules currently in place.
Nachdem die bestehenden Regeln überprüft wurden, wurden Änderungen vorgenommen.
After the existing rules were reviewed, changes were made.
'Bestehend' modifies 'problems' and describes them as currently present or ongoing.