Tim Hunt

I think that, for performance, log events get buffered, and written to the database in chunks, which may explain weirdness if you triggere an event and immediately expect it to appear in a query.

Now I look again, it seems that the mobile app is happy just logging events when they hit the Moodle server, not when they were acutally done offline.

The only way I can think of to do what you want is a bit hacky. You need to use reflection to change the protected $event->data['timecreated'] between creating the event then triggering it.

This is nothing to do with the quiz. I will move this to the installation problems forum.

Well, you have not said anything about what you want your custom form element type to do. It is much easier to give advice if we know the result you want.

It is possible to define a new field type in a plugin and use it. I did https://github.com/moodleou/moodle-tool_editrolesbycap/blob/main/capabilityformfield.php ages ago - but I have no idea if that is still the best approach.

This query might help: https://docs.moodle.org/dev/Overview_of_the_Moodle_question_engine#Detailed_data_about_an_attempt

What about other bit forms in Moodle (e.g. course settings, ...)