Hi,
I assume you installed those packs using the manifest URL, which would explain why they use your data storage instead of assets. If you open the manifest url, you should see a “download” line, and if you download the zip file and use the Import Wizard, it will be automatically uploaded to the assets library and optimized to use it.
You can see the instructions for premium content which would be similar for your situation : Installing/updating Licensed Premium modules - Docs - The Forge
Also note two things :
1 - we are currently close to releasing an update which would do the optimization of manifest-installed content automatically.
2 - there will always be a bit of Data used by the modules, though it would be a lot less than what it currently uses, but the compendium packs do need to be copied/installed on your data folder. It would generally be a few KBs or a few MBs instead of hunderds of MBs.
I hope that helps