Nothing new about the number of hidden chambers found around ancient Jewish villages, and the tendency to attribute them specifically to the major Jewish revolts as opposed to general banditry, zealotry, etc, but this set might be of interest given the circumstantial linkage being made to Bar Kochba's revolt and the specific question of whether he ever managed to have active resistance in Galilee.
https://www.timesofisrael.com/ancient-jewish-revolt-era-safe-rooms-revealed-in-the-galilee/