WPML: Add custom fields to the config

[merkushin]

There were a number of fields without configuration.
I started with answers to make them translatable — that helped with question translation.

Proposed Changes

• Add custom fields to the config[
• Translate the product ID if possible.

Testing Instructions

1. Create a multiple choice question.
2. Create translation for the question.
3. Make sure you see the question title and the answers in the WPML translation editor.
4. Check translated question has translated strings.

Longer test scenario

1. Follow our documented testing instructions.
2. Instead of editing questions in the translated lesson, go to the original questions and click on "pencil" to edit translations for the target language.
3. Go to frontend and check you see translated questions in the quiz.

Translated Product ID Testing Instructions

1. Install and activate WPML, Sensei Pro, WooCommerce, WooCommerce Multilingual & Multicurrency.
2. Follow their instructions to set up properly.
3. Create an original course with lessons. (You can just create a new course, choose the default layout with default 3 lessons and publish it — content doesn't matter.)
4. Go to Course Settings in the sidebar.
5. In the Pricing section, create a new product and assign the course to that product.
6. Go to Products, find "Translate WooCommerce products" in the filters section above the product list and click it.
7. Create translation for the product you created on the step 5.
8. Now go to Sensei LMS -> Courses. Click on the "plus" button to create a translation for the course from the step 3.
9. Follow WPML instructions in the WPML editor.
10. Open the translated course and check Course Settings > Pricing.
11. Make sure your translated course is assigned to the translated product.

Pre-Merge Checklist

• PR title and description contain sufficient detail and accurately describe the changes
• Acceptance criteria is met
• Decisions are publicly documented
• Adheres to coding standards (PHP, JavaScript, CSS, HTML)
• All strings are translatable (without concatenation, handles plurals)
• Follows our naming conventions (P6rkRX-4oA-p2)
• Hooks (p6rkRX-1uS-p2) and functions are documented
• New UIs are responsive and use a mobile-first approach
• New UIs match the designs
• Different user privileges (admin, teacher, subscriber) are tested as appropriate
• Legacy courses (course without blocks) are tested
• Code is tested on the minimum supported PHP and WordPress versions
• User interface changes have been tested on the latest versions of Chrome, Firefox and Safari
• "Needs Documentation" label is added if this change requires updates to documentation
• Known issues are created as new GitHub issues

[github-actions]

Test the previous changes of this PR with WordPress Playground.

[github-actions]

Test the previous changes of this PR with WordPress Playground.

[donnapep]

This kinda worked for me, only didn't. 😅 I started by creating an English MCQ question. When I clicked + to add a Spanish translation, the answers as well as the answer feedback was shown in the WPML translation editor. When I opened the Spanish question though, the answers were empty:

Then when I tried to test again with a new question, I was no longer seeing the answers in the translation editor. There's nothing in the WPML logs but an "Unable to authenticate" error.

What should I be testing for the product ID?

[github-actions]

Test the previous changes of this PR with WordPress Playground.

[m1r0]

I'm guessing there was some caching because the answer translation worked fine only after the second try.

The product relation field worked as well. 👍