My guess is the key lies in the character behavior rather than any behavior file attached to the furniture object itself. Furniture behavior files are a little easier to decipher, although they can still be beasts to understand if you're not familiar with how they work. I have only about a 20% understanding of the simpler ones at this point, I'm afraid. All I really know is what strings to look for in order to get the furniture animations to fire along with the character animations.
Character behavior files are another can of worms altogether. A very big can of worms. Like I said before, the idle phase is where the NPC more or less controls how long they remain in the animation. It would help to look for and study vanilla furniture objects that NPCs will interact with for longer periods. There might be priority flags at work with those. I don't know for sure. Even the most basic of workbench animations seem to last for wildly random intervals. I do know that all of the furniture objects I've made seem to keep the NPCs involved for roughly the same length of time, 20-30 seconds, but sometimes they will continue "interacting" for a minute or more. I've made a few with idle flavor animations, which are basically secondary, supplemental animations randomly mixed in with the base PoseA_Idle animation, and NPCs tend to remain involved with those objects a bit longer. It could also depend on what keywords the furniture object has. I use WorkshopRelaxationObject on the stuff I've built and that seems to get the NPCs to use the objects quite regularly.
Here's a great in depth Havok guide that I've perused on many occasions looking for clues to figuring this stuff out: https://forums.nexus...-4-havok-guide/
Funny thing is, the author gives me credit for helping him out in some way and I am really clueless as to what I did.
If you haven't already done so, I would also recommend downloading the Fallout 4 Animation Kit: https://www.nexusmod...out4/mods/16694
It includes a great tool for converting hkx files into xml, so then you can at least begin to study the behavior, animation, skeleton, etc, files associated with Havok animation. The kit also comes with a comprehensive PDF that explains how to make use of the included tools.
I hope this helps. Feel free to shoot me a PM if you have any other questions. Maybe I can give a little more insight.
Edited by ChuckYufarley, 18 May 2022 - 11:37 PM.