It could be, we never tested JNews with “Crop Thumbnails” plugin. Usually we regenerate thumbnail after updating image, is there menu to regenerate image from the plugin? Because, there are some image sizes that used on the theme.
About sidefeed filter, could you try to re-add the category list?
For string translation, you could do it with JNews – Frontend Translation plugin. After you activate it, navigate to JNews > Translate Frontend. Then you translate those text there.