I've just submitted v4.3.4 of Edit Orders to the Zen Cart Plugins for review; once available for download, I'll post back here.

This release contains changes associated with the following GitHub issues, see https://github.com/lat9/edit_orders for additional information:

#65: Enable `ot_onetime_discount` to both add to and deduct from an order's total.
#72: Additional notifications for plugin support.
#73: Tax-handling corrections, enables proper integration with plugin order-totals.
#74: Correct PHP 7.1+ warning
#75: Entered product price no longer overrides calculations. In support of that change, two additional Edit Orders configuration settings are created!
#76: Changes to the order's `shipping method` don't "stick".
#77: Re-align `/YOUR_ADMIN/orders.php` notifiers with those present in Zen Cart 1.5.6 and later.