Problem:

The problem here is that the elementor dynamic content option isn't showing the correct image from an image field when the Elementor Custom Skin PRO is active

Solution:

Unfortunately the dynamic content option is something that is maintained by elementor itself and as such will need to be resolved by the elementor team.

The recommendation here is to get in touch with the elementor support team.

Problem:
Custom data validation during CRED form submission

Solution:
You can use the Toolset form's hook "cred_filter_field_before_add_to_form" to dynamically set the required field for your form.

You can find proposed solution, in this case with the following reply:
https://toolset.com/forums/topic/custom-data-validation-during-cred-form-submission/#post-2207949

Relevant Documentation:
=> https://toolset.com/documentation/programmer-reference/adding-custom-code/using-toolset-to-add-custom-code/