What is a "KALP114A" ATC regulation?
Within Europe, whenever there is need to reduce the number of flights through a certain airspace, the Network Manager (Eurocontrol) puts in a so called "regulation". This results in flights planned through the regulated airspace being delayed or re-routed.

Regulations are given an ID; those starting with KALP are from the Karlsruhe Upper Area Control (EDUU), southern sectors (Alps) above Flight Level 315.

Since your flight was over three weeks ago, I can't check the exact "regulation Id" in the public database, but it is likely that it was related to staffing issues at Karlsruhe upper area control centre.

An example of a current regulation starting with "KALP" is below: 



Karlsruhe UAC has severe staffing problems and is causing many traffic delays this year.



A delay of 6 hours due to a regulation sounds extreme to me. I don't know what the origin and destination of the flight was, but typically a re-routing avoids the regulated airspace with only a short delay.