BTW, testing now, the showon works OK there.
The problem with password is, the core password function in Joomla is wrongly written as it does not count with dynamically added form fields. This is different to showon which has initialize function and can be reinitialized after loading new dynamic items (which is even not right as it does not count with dynamically items from start but as developer you can somehow correct it).
And it even seems that this does not work in subforms so we need to write some bug report for Joomla core.