@Gregor have you seen platform journeys where an actual business term was used as an abstraction on the self-serve platform? And as such pull the ubiquitous business language defined using DDD towards the platform? Or where is always technical domain terms? If someone else has seen examples of this, please share.

I have seen this. It all depends on whether usecases relevant to the business are realized as part of the IDP as well. So, mainly, I have seen lingo converge when reporting (reports and dashboards) and approval (manual approval steps for business owners to formally approve QA results and production deployment attempts) are being handled by the platform for those stakeholders as well.