All the created CID segments are nicely visible in CIJ RTM side but you cannot use them as basis for other segments. When you have some external data on CID side and you create a segment there, it would be really useful to be able to use that segment of accounts (for example) connected to actual contacts and then leverage that in journeys.

With the current setup you take all your data into CID side and create segments there (where the segment builder is far from user-friendly compared to CIJ segment builder experience).