I've noticed the word ルンパッパ (runpappa) is used in the KEMU VOXX series of songs, but I don't know how to translate it. Using google translate just returns rumpappa, which isn't an English word. I've tried googling it, but it just returns Ludicolo, which certainly isn't relevant. The top result says it means to sin, but it also says their source may be unreliable. The three songs to use it are Haikei Dopperugenga, Inbijiburu, and Kamisama Nejimaki. Thanks!
That is a mimetic word to feeling the rhythm of a song. So translate it into "Rum-pa-ppa".
Rumpappa is the word combined "Run-run" and "Um-pa-ppa"
"Run-run" is a mimetic word expressing good/happy mood. https://ja.wikipedia.org/wiki/%E3%83%AB%E3%83%B3%E3%83%AB%E3%83%B3
"Um-pa-ppa" is the title of song. This word is familiar with Japanese as they sing it when in primary school.
"Um-pa-ppa" is "Oom-Pah-Pah" in musical "Oliver!". https://ja.wikipedia.org/wiki/%E3%82%A6%E3%83%B3%E3%83%91%E3%83%83%E3%83%91
Could this be ウンパッパ? In English, "Oom-pah-pah" is a conventionalised representation of the sound of a large brass musical instrument such as a tuba or trombone. It is the title of a rousing song in the musical "Oliver!", sung in the film version by the great Shani Wallis.