[vidarh]

You're right that you can do probably that if you only ever keep the layers separate. The moment you e.g. provide export functions that combine the layers, you're currently in a grey area. With the new license, it's no longer a grey area, but you explicitly need to release your source data to be in compliance.

[liotier]

Not as long as the other items have no dependency on or interaction with the OSM layer.