[Xposed Framework Modules] nijel8:
I see two problems in you logcat:

1. "E Xposed : xswiftkey CURRENT THEME: null" means you haven't applied a theme in swiftkey settings with module running(fresh module install?) or module didn't save it (which might be another issue) but non of these would make swiftkey crashing...

2. You said you have granted storage permissions, but look at these lines in your logcat:

02-19 21:19:56.480 988 988 W PackageManager: Not granting permission android.permission.WRITE_EXTERNAL_STORAGE to package com.touchtype.swiftkey.beta because it was previously installed without

02-19 21:19:56.480 988 988 W PackageManager: Not granting permission android.permission.READ_SMS to package com.touchtype.swiftkey.beta because it was previously installed without

02-19 21:19:56.480 988 988 W PackageManager: Not granting permission android.permission.GET_ACCOUNTS to package com.touchtype.swiftkey.beta because it was previously installed without

02-19 21:19:56.482 988 988 W PackageManager: Unknown permission com.swiftkey.languageprovider.READLANG in package com.touchtype.swiftkey.beta

02-19 21:19:56.482 988 988 W PackageManager: Unknown permission com.swiftkey.swiftkeyconfigurator.READCONFIG in package com.touchtype.swiftkey.beta

02-19 21:19:56.483 988 988 W PackageManager: Not granting permission android.permission.READ_EXTERNAL_STORAGE to package com.touchtype.swiftkey.beta because it was previously installed without

02-19 21:20:00.954 988 1412 W PackageManager: Not granting permission android.permission.WRITE_EXTERNAL_STORAGE to package com.touchtype.swiftkey.beta because it was previously installed without

02-19 21:20:00.954 988 1412 W PackageManager: Not granting permission android.permission.READ_SMS to package com.touchtype.swiftkey.beta because it was previously installed without

02-19 21:20:00.954 988 1412 W PackageManager: Not granting permission android.permission.GET_ACCOUNTS to package com.touchtype.swiftkey.beta because it was previously installed without

02-19 21:20:00.956 988 1412 W PackageManager: Unknown permission com.swiftkey.languageprovider.READLANG in package com.touchtype.swiftkey.beta

02-19 21:20:00.956 988 1412 W PackageManager: Unknown permission com.swiftkey.swiftkeyconfigurator.READCONFIG in package com.touchtype.swiftkey.beta

02-19 21:20:00.956 988 1412 W PackageManager: Not granting permission android.permission.READ_EXTERNAL_STORAGE to package com.touchtype.swiftkey.beta because it was previously installed without

I am almost sure with so many not granted permissions swiftkey would crash...

And about this line xposed-swiftkey relaited: "E Xposed : Caused by: java.lang.ClassNotFoundException: Didn't find class "android.widget.Editor.SelectionActionModeCallback" on path: DexPathList[[zip file "/data/app/com.touchtype.swiftkey.beta-2/base.apk"],nativeLibraryDirectories=[/data/app/com.touchtype.swiftkey.beta-2/lib/arm, /data/app/com.touchtype.swiftkey.beta-2/base.apk!/lib/armeabi-v7a, /vendor/lib, /system/lib]]" I can assure you has nothing to do with my module... My module is not hooking anything outside of swiftkey package. Must be something else you have installed. And that not found class is part of android framework and I can't get it why would a module will look for it in swiftkey package?!?!?! Using wrong swiftkey classloader maybe?!?!?!

So fix your storage permissions even if you have to uninstall and clean install swiftkey.