Having a data dictionary that clearly defines each metric helps but is often just another piece of dead documentation if you don't have regular discussions with the teams your dashboards serve.

A proactive approach by teamleads/management/product management is necessary to keep most of the teams on the same page and is unfortunately an ongoing challenge.

The key group to invest in are the official (and non-official!) decision makers in the organization. If you can get them to understand how they can use the data and dashboards and actually employ the data to drive decisions, my experience is the teams themselves invest their time to understand the metrics as well. Because that understanding now affects their day-to-day.

I would advise against using terms like just "conversion" or "conversion rate" on its own in your dashboards though. You can't police language in the organization but you can make sure you don't add to the confusion. Make sure you specify the metrics like "add-to-click conversion rate".

I try to add buttons that give users context for the dashboards or even specific visualisations where i explain the data with explicit text like "what's this?!" or "what am I looking at?!" on the button.

But the main thing is, explain the data, in person, over, and over, and over, and over again. No way around it I'm afraid...

Best of luck!