Users are responsible for writing and troubleshooting their own custom themes. This is not a coding forum. Basic guidance is provided here: https://www.manager.io/guides/10368. If you do not have the skills, any competent web designer with Liquid programming experience should be able to help.
Custom themes only change the general appearance of a transaction form. All available information is already displayed using the built-in Plain theme. Anything not there must be added with custom fields. See Use custom fields | Manager. Some of your variables do not exist anywhere in the database. But you can determine which are available by examining the code for the Plain theme.
Be aware that custom field titles do not display unless there is content within the field itself for the specific transaction.
Nothing you do will change the format of entry screens for transactions or forms. Those are fixed. You will see the result of your custom theme only when the completed form is viewed.