I don't have workflow, workbench, desktop, it's a "black box" to me.

https://forms.life/2019/01/31/transitioning-from-workbench-and-designer-with-jee-to-osgi/From this article, move everything from JEE to OSGI is quite possible and not difficult. Just they didn't post how.^_^

Also, the users and permissions. 

How about the bundles? OSGI configuration? Any way to copy over the bundles/configuration/content package as single?

Can you put create a package for whole code source and put somewhere we can download? I understand the HTML part, just don't understand how to put with with adaptive form. Adaptive form only deal with AEM defined components, how to relate the AEM forms component with HTML elements?

This is exactly the problem we had before^_^.Solution: save your payload to database or your own whatever repository before you call workflow. Then in workflow, read your saving and put as workflow parameters or replace data.xml.We are doing this now and no problem in PROD for a few months.It's very weird that something working on author but not publisher.I don't think any OSGI setting can save you since AEM servlet doesn't take any configuration, including locale.

In the request parameters, put afAcceptLang as request URL parameter, for example: http://localhost:4503/content/forms/af/xyzform.html?dataRef=a=b&afAcceptLang=es

Sorry, revert back, the input is not correct. The current solution is write our own servlet to save/retrive the data to database ourselves then update JCR as needed. The AEM servlet code is very old and simple and may not fit the need.

Our problem is more weird than this, our exact the same code and form work on author, but when submit through publisher, no matter what's the trick you listed below, the Spanish character in the submitted input fields messed. The final solution is when AEM start, put -Dfile.encoding=UTF-8 in the aem start command, then problem resolved.