I am using T4 Framework a lot lately and i want to point some things that need improvement.

1. Aria Roles
Every row you create on template has a title, the title you type also is inserted automatically as an ARIA role attribute to the element, which is wrong because those title are most of the times description titles for the administrator. Also those titles are unique so we cannot set the same name on other rows.
Suggestion: you should have an extra field as aria attribute so we can set the attribute value we want.

2. Element Custom Params Attributes
When you create a column, you select the kind of content that will fill the column. So if you select as Column Type , the type element there is field called custom params. What are those and how we can use them?

3. Item Icon in Navigation mega menu.
At navigation tab on mega menu settings there is an attribute for each menu item to have an Item icon.
i see that on frontend it adds a .material-icon class. Where is the list of icons we can choose from?

4. tag -i- for your icons
Using the <i> tag to have font awesome icons on the t4 framework and t4 system plugin is wrong for accessibility issues. If you run a test on page with t4 framework from https://achecker.ca/checker/index.php (a tool to check the accessibility settings of a website), then you will see that it will give errors.
This is because the i element is not handled as well by screen readers as the em and strong elements. Also all these decorative icons such as caret, arrow etc should have an attribute aria-hidden="true" or aria-label so that it is handled correctly on accesibility checking.

I understand that you never implied that these templates are Accessibility Ready but because all these are handled in a way that we, as the end users, cannot edit and we cannot fix them somehow.