That's true, albums linked through weblocs are not part of the album tree, therefore they are not searchable from the outside.
Albums made with Adobe spark will probably never be searchable from a jAlbum album (and vice-versa), and it's also hard to imagine how a search throughout hundreds of albums could work within jAlbum albums. This takes loading every album's database and running a search on all of them, which could take long minutes. Not something any visitor would wait for. Google search is something that was optimized for this task from the beginning. You can use that tool.
https://support.google.com/programmable-search/answer/4513903?hl=en