import json

with open("mini.json") as f:
    mydata = json.load(f)

print('mydata[1]["name"] =', mydata[1]["name"])
# print('mydata[0]["test"] =', mydata[0]["test"])  # Produziert einen Fehler
print('mydata[0]["inhalt"][1] =', mydata[0]["inhalt"][1])

print("Vorher")
print(mydata[1]["inhalt"])
mydata[1]["inhalt"][2]=1234

print('Nachher mydata[1]["inhalt"]')
print(mydata[1]["inhalt"])