Ansible Filter Plugin/Python - append results to existing keys

I'm pretty new to understanding a few Python things, but this is taking me hours now, so i might need a bit help. I'm creating an custom filter plugin for Ansible. This is an example Playbook:

hosts: host1:host2
  tasks:
    - name: random numbers between 0-10
      command: shuf -i 0-10 -n 1
      register: out
      until: out | customfilter1(file, ansible_hostname) or out.stdout == "2"
      retries: 50
      delay: 0
      vars:
        file: ./file.json

It makes random numbers and does that until the random number is matching 2. Here is the customfilter1 which should make a nice json out of it:

#!/usr/bin/python
import os
import json

class FilterModule(object):
    def filters(self):
        return {
            'customfilter1': self.customfilter1
        }

    def customfilter1(self, obj, file, ansible_hostname):
        if obj["attempts"] == 1:
            print(obj)
            newdata = {ansible_hostname: {"Attempts": {obj["attempts"]: {"Result": obj["stdout"]}}}}
            json_file = json.dumps(newdata, sort_keys=False, indent=2)
            with open(file, 'a') as f:
                f.write(json_file)
        else:
            with open(file) as f:
                data = json.load(f)
            data[ansible_hostname]["Attempts"][obj["attempts"]] = {"Result": obj["stdout"]}
            json_file = json.dumps(data, sort_keys=False, indent=2)
            with open(file, 'w') as f:
                f.write(json_file)

        return False

I had like 200 versions of this so this is the most recent one that is working pretty good for a single host, but when using it for multiple hosts the second one drop

fatal: [ampere]: FAILED! => {"msg": "The conditional check 'out | customfilter1(file, ansible_hostname) or out.stdout == \"2\"' failed. The error was: Extra data: line 21 column 2 (char 273)"}

The json file contains this:

{
  "host1: {
    "Attempts": {
      "1": {
        "Result": "4"
      },
      "2": {
        "Result": "5"
      },
      "3": {
        "Result": "7"
      },
      "4": {
        "Result": "0"
      },
      "5": {
        "Result": "2"
      }
    }
  }
}{
  "host2": {
    "Attempts": {
      "1": {
        "Result": "5"
      }
    }
  }
}

The error seems to appear in the line with the two curly brackets "}{"

It might be a different issue but is there a way to get around of this?