Dear Swiftkey / Microsoft,
great that you have started to support alternative keyboards, such as Colemak and Dvorak. This is a feature request for linking your Microsoft Swiftkey to MSKLC, Microsoft's Keyboard Layout Creator, to allow users to make and use their own keyboards for use in Swiftkey, as we do in Windows.
https://www.microsoft.com/en-us/download/details.aspx?id=102134