This is the 14787th most frequent German word.
phänomenalen
"Phänomenalen" means "phenomenal" or "extraordinary" in English.
In this context, "phänomenale" describes an exceptional quality of a specific noun ("Leistung").
Das war eine phänomenale Leistung im Konzert.
That was a phenomenal performance in the concert.
Here, "phänomenalen" modifies the noun "Farben" to emphasize their impressive aspect.
Wir bewunderten die phänomenalen Farben des Sonnenuntergangs.
We admired the phenomenal colors of the sunset.
In this usage, "phänomenalen" adds emphasis to "Zuspruch" to indicate it was exceedingly positive.