Once you’ve installed the mod and run the game at least once, you’ll find the booster configs in the following location:
/config/unchained/<context>/<booster><context>Booster.json
/config/unchained/capture/hiddenCaptureBooster.json/config/unchained/capture/ivCaptureBooster.json/config/unchained/capture/shinyCaptureBooster.json/config/unchained/egg/hiddenEggBooster.json/config/unchained/egg/ivEggBooster.json/config/unchained/egg/shinyEggBooster.json/config/unchained/fish/hiddenFishBooster.json/config/unchained/fish/ivFishBooster.json/config/unchained/fish/shinyFishBooster.json/config/unchained/resurrection/hiddenRezBooster.json/config/unchained/resurrection/ivRezBooster.json/config/unchained/resurrection/shinyRezBooster.json/config/unchained/spawn/hiddenSpawnBooster.json/config/unchained/spawn/ivSpawnBooster.json