Module development and code questions

With THEME_form_system_site_information_settings_alter i can change the max field length of the site_slogan form, like:

function THEME_form_system_site_information_settings_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  $form['site_information']['site_slogan']['#maxlength'] = 500;
}

Apparently the form for the slogan in the site information translation is different,

thus forexample in /admin/config/system/site-information/translate/en/edit

There is other form for the slogan.

I created a code to automatically flag nodes and comments. When I put only the code to flag the nodes, it works. But when I add the code to flag the comments it doesn't work anymore.

Which code should I use ?

I have created a small module (Drupal 8) to display an "Agree to Terms" link in the Drupal Commerce shopping tunnel.
This link displays the store's condition page.
I want to display the rendered store entity instead of the conditions page. How to do this ?
I created in my type of store, a display named "Terms and conditions". I want to make this display in a modal window when the user clicks on the link.

Here is my code :

I am really lost, and need some guidance.

Drupal is capable of doing something, that I want to leverage/exploit. 

But I can't figure out how to access this component in an isolated manner, everything seems to be deeply entangled, and every class I find that does what I need, requires 5 container classes and injections and dependencies...

So I'm out here asking to see if someone can help, before I need to literally read thru the entire code base to figure it out.

I'm using HOOK_form_alter to store a string for a taxonomy entity. Because I want to be graphical, I'm using the Form API radios type combined with special CSS for my customers to choose which color they want.

Relevant portion of mymodule.module

I created a small custom module to automatically flag new or updated entities.

My code doesn't work, there must be some errors. Can you help me ? Thank you

https://git.drupalcode.org/sandbox/zenimagine-3170711