For the time being I need to continue to run Evernote but want to use Joplin as well. I have my current Evenote base imported to Joplin. Is there any way to keep Joplin updated with the new content in Evernote?
Not easily, you’ll need to export your changed notes from Evernote regularly and manually import them into Joplin. Notes in Joplin won’t be overwritten automatically so you’ll need to delete the old versions manually too.
I do not understand why Joplin cannot do the same as Synology Note Station. In Note Station you can login into evernote and then download directly from evernote server to Note Station. The big advantage is that you can download all your notebooks in one process and you will tranfer your whole structure.