haven't solved anything yet
Seems tricky to handle it with only the lock. Do you just want to avoid adding additional sensors to the door?
If you could add a multisensor to the door, this is what I imagine could work:
1) User lock manager runs routine to let you in without triggering the siren/lights
2) Something like this catches the door close and puts it back to night mode https://github.com/thale57/SmartThingsPublic/blob/master/smartapps/thale/execute-routine-contact-time.src/execute-routine-contact-time.groovy (um, let me know if that link doesn't work, never linked to my code before...and didn't really expect others to see it so be kind. This app is used on my bedroom door to trigger good morning at the appropriate times or turn off night if I get up/turn it back on if I go back to bed)
3) Multisensor does vibration so there HAS to be something out there that triggers on vibration, one of those "if X is moved apps" that we see advertised all over the place, but which I can't think of the names of off hand. So basically, if vibration (someone trying to break in) in night mode, trigger the alerts.
Now if nothing can be added to the door, that takes some thinking about what rules would guide the logic. Hmm, never written anything with my [Kwikset] lock either, since Erik Thayer has the coolest lock manager ever.
If nothing can be added to the door:
1) stays the same as above
2) Something else would need to trigger going back to night mode [based on whatever you have in your house]
3) Need something else - motion or other - to trigger the break-in. Are you thinking physical tamper or attempting random codes?