Hello sjapartments, no, the bookmarks created through BSP2 are fully standard, they are created using the Firefox API, so they are created by Firefox itself, and they do not differ from when they are created from the native bookmark sidebar.
There must be something else.
Maybe Edge has a bug in importing bookmarks from Firefox ? Cf. https://answers.microsoft.com/en-us/microsoftedge/forum/all/unable-to-import-bookmarks-favorites-from-firefox/539ce5d5-1e8a-4ea6-bc92-a6808de6a19d, you do not seem to be alone having problems