Observation: when doing a DDD session with someone who is using a system you want to change or replace, you will discover that both language and assumed constraints will follow the mental model people have of the current system.
Make sure to take the time to make people comfortable to think out of the box and to use new words for things they think are set in stone. You might need state “obviously wrong” things to shake expectations up.
Only when people are ready to let go of old models you can start exploring new ideas and create a common language that might get ubiquitous.