I suggest you try updating to the master_2019.2 version. Follow the instruction under the Version Update Process topic on the left. If you could load your current version on your local PC first and run this update there, it will help you work out any issues you run into.
The primary issue you might encounter is the patch that implements foreign key support in the database. This patch checks your database for orphaned records (such as a si_cron_log record with no associated si_cron record). The patch process will stop if it finds any orphaned records. It does list the issues found and typically the solution is to delete those records and then run SI again so the patch process can complete.
Since you are running with a version of PHP 7.3, you will stay on this SI version. However, if your cpanel allows you to maintain your PHP version (as mine does), you might consider updating to PHP 7.4+. If your SI application is the only thing running on your host, this should be straight forward. If you have other sites running on your host, you need to make sure they will support the change. Once on PHP 7.4+ you can install master_2020 which will get you on the most current version of SI. Also, you should notice a significant performance improvement.
Let me know how this goes.