Nested macros and migration support from Server to Cloud

We are an Atlassian App editor and we are currently facing a big challenge buidling a cloud App.
We actually have a well established app on server that is based on nested macro model and we lately we have been working on building the equivalent app on Cloud.
Still Atlassian just landed the new editor and the nested macros are no more supported especially if we don’t have the cloud app on the marketplace.
The challenge concerns the migration from server to cloud for some of our customers.
Does anyone found a way to migrate old structure to the new one ? Do we need to implement a special fix to our customer to get the data and put it to the new model in cloud.
Atlassian provide support for already used macros in cloud which is not our case as we didn’t published our app yet on the marketplace.
Any idea or feedback shared would be more than welcome.