sorry to here that. And i have bad news for you. The Crop-Thumbnail-Plugin will not be corporate with the "ImageMagick Engine" Plugin.
Why: if i read the "ImageMagick Engine" Plugin Description right its a Resizing Plugin. It resizes the WordPress images and cropped-images in the same way (size, filenames) like WordPress and override the default (wordpress) ones.
My Plugin do technically exactly the same, it override the default ones. Your plugin tweak on the quality, mine on the clipping.
You may get the pleasure to get Images cropped by Imagick - beside from your plugin.
I used the standard wordpress-function to do the cropping. A plugin that want to enhance the quality of the output of my clipping has to exchange the intern wordpress-resize algorithem.
The strange thing is: i do a look into the wordpress code. WordPress may use the imagick library - the code is there. And eventually they use it already. In fact they use a code-pattern to use either
But i don't know under what circumstances they use it.
Maybe i take deeper look later.