Cannot edit some of the new templates

Issue Summary

We have recently added some cool new templates within Confluence Cloud (you can check further details on this Atlassian Community post: A new create flow and templates experience is coming to Confluence Cloud!). They are pretty cool, we know, but even so, sometimes we always want to change a default template to give our company's personal touch to it, so that's why we have the edit option on default templates.
For some of these new templates we have implemented on Confluence, we are unable to edit them - they just keep loading in the browser.

Steps to Reproduce

1. From your Confluence homepage, go to Settings > Global Templates and Blueprints
2. Click over the Edit button on any of the below templates:

• AWS architecture diagram
• Business status update
• Premortem
• Brainstorming
• Customer impact assessment
• Experiment planning sample-bp1-name results
• Marketing united
• Design sprint
• Customer interview reports
• Default project poster plan index template - Oops - an error has occurred
• Executive business review
• Writing guidelines
• Weekly meeting notes
• Leadership team health monitor
• Default marketing plan template
• Disruptive brainstorming
• Interview feedback

Expected Results

The editor opens up and we are able to edit the template.

Actual Results

A spinning wheel keeps spinning forever at the browser.

Notes:
It is possible to check 3 different errors in the response of the request with file cgraphql?q=templateEditorContent that we can receive on these templates:

• value: <div class="error fatal-render-error">Error: RuntimeException occurred while performing an XHTML storage transformation (Expected ac:placeholder end element but got: <at:i18n>)</div>

  On the templates:

• • AWS architecture diagram
  • Business status update
  • Premortem
  • Brainstorming
  • Customer impact assessment
  • Experiment planning sample-bp1-name results
  • Marketing united
  • Design sprint
  • Customer interview reports
  • Executive business review
  • Weekly meeting notes
  • Default marketing plan template
  • Disruptive brainstorming
  • Interview feedback

• <div class="error fatal-render-error">Error: RuntimeException occurred while performing an XHTML storage transformation (Expected ac:placeholder end element but got: *)</div>

  On the templates:

• • Leadership team health monitor
  • Writing guidelines
• And the below one, on the Default project poster plan index template:
  

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available