First of all, it'll be really hard to address your concerns since you're in xenial which is outdated for more than a year now. The bugs you encountered might already be fixed but will never be fixed in xenial. Also please tell us which device you have. It may also be possible that your device have a port that is unmaintained or not in good quality.
I've never encountered your issue with the lockscreen and alarm. Perhaps you used passwd to change your password? You shouldn't do that since the settings app does something else and the system expects those. I've been using my UT device for my alarms for a decade now and I don't remember it failing. We don't have any complexities in time such as daylight savings though which perhaps causes these issues?
As for Libertine, it really is under-developed and never found it reliable. It works for some cases but definitely not with GUI apps.
For encryption, someone has experimented with it but nothing official yet. At the end of the day, someone has to put the effort on it but so far no one succeeded yet.
