Ryuzine Press 1.0 works as expected in WordPress 5 (tested in 5.0.2).  If you upgrade to WP 5 your existing Ryuzine Press Editions should remain unaffected.  We updated one of our development server WordPress installs from version 3.8 directly to 5.0.2 without any problems.

In a new installation, however, you still have to make sure to go through the Ryuzine Press > Options and “Save” even if you didn’t make any changes, just to make sure all the entries are written to the database.  You should always do this after a Ryuzine Press version update as well, in case any options have been added or changed since the previous install.

Note that Ryuzine Press 1.0 still needs to use the TinyMCE “Classic” post editor.  If you upgrade from an earlier version of WordPress or install the “Classic” editor plugin there should be no problem.  Ryuzine Press will still be able to use the classic editor even if you’ve set other posts and pages to use the new Gutenberg editor.  In a new WP 5 installation you will probably have to install the “Classic” editor plugin.

There IS an update to the Ryuzine and Ryuzine Press in the works, though the release keeps getting pushed back, but the currently available version will still work until the update becomes available.