I will have a closer look at json files, but its too much right now.
With @TIMAI2 s answer I still get an error message when pressing "do it" on the "call web 1...":
"Error from Companion: invoke: no method named ´JsonTextWithDictionaries´in class com.google.appinventor.componens.runtime.Web"
It sounds like your companion app is out of date if that is the case. The JsonTextDecodeWithDictionaries block was added when we added the dictionary type to the blocks language. This was done in nb182 back in February of this year. If you haven't already, consider updating your companion app via the Play Store or by downloading the latest version from the App Inventor server scanning the QR code under the Help > Companion Information menu option.
If it's got pairs {tag:value,...} use the dict lookup by key block
If it's got pairs [[tag,value],...] use the lookup in pairs list block
If it's a list [?,...] of similar items without tags, use a for each item in list block or a select item n from list block.