Since WordPress have a built in widget with a wysiwyg I decided to not contintue to support the plugin. And with full site editing in the works its hard to say if it will stop working all of a sudden. There might be workaround with stopping the block editor widgets or something, I havent looked into it. I would recommend moving to another solution before it turns into an issue. ??
Black Studio TinyMCE Widget might also be another option.
If you disable the plugin WordPress doesnt know how to output them and they will disappear.
With regards to converting them its hard to say, because it depends on what you want to convert them to.
You can read here about where widgets are stored. Reading the WP Editor Widgets data might not be hard. And then putting them into something else depends on what other solution you want to use.
It might be easier to leave the plugin active and manually move widgets and disable the plugin once its done.