How to refresh info in Task or load Task with latest info?

If the Task interface queries the record data directly, rather than has it passed in through the process, it should reflect any changes made through the update related action. If the user already has the task open while an update is made, I don't think there is an out of the box solution to automatically refresh the Task. To work around this, you could have the process check for any updates made after the Task is submitted and route the user to a notification screen in the event there were changes made concurrent to the Task.

If you do end up deciding to go with the second solution, there is another topic going on currently that is providing locking strategies for related actions that you may find useful:
community.appian.com/.../how-can-i-prevent-multiple-users-from-accessing-the-same-related-action

If data is coming from DB, then you can use fetch data in load section of the SAIL, and use that local variable within the SAIL form to display data. Every time user launches the task (even if user leaves the task, clicks somewhere else and then opens the same task from task list), load gets executed - so that ensures you have the latest data shown to user which may be modified from outside of the current process.

Alternately, when user submits the record, you can check if the data was modified after user opened the task - if so, you can redirect user to the same interface with an error - saying data is stale etc.