Put the initialization priority to -999 and override after_load so the defaults get replaced with the real names.
Python:
# game/x-patch.rpy
init -999:
default nezuko_name = "Nezuko"
default kanao_name = "Kanao"
default mitsuri_name = "Mitsuri"
default shinobu_name = "Shinobu"
default kanzaki_name = "Kanzaki"
default daki_name = "Daki"
default suma_name = "Suma"
default makio_name = "Makio"
default hinatsuru_name = "Hinatsuru"
default spider_name = "Spider Mother"
default kanae_name = "Kanae"
default kie_name = "Kie"
default muzan_name = "Muzan"
default tamayo_name = "Tamayo"
Edit v2: Added label overrides for "kitchen_day" and "training_day" to handle Nezuko, Kanao and Kanzaki.