[One (M8) Q&A, Help & Troubleshooting] MasterMarius:
It's about the language of the menus and labels not the keyboard language, there's mine same as yours, anyway I used app called Locale Language with a cmd line and after that, all my phon is in the right language but without the possibility to see that option marked in the language menu (only 5 languages are there) the cmd line is:

C:\adb>adb shell pm grant jp.co.c_lis.ccl.morelocale android.permision.CHANGE_CO

NFIGURATION

Bad argument: java.lang.IllegalArgumentException: Unknown permission: android.pe

rmision.CHANGE_CONFIGURATION

usage: pm list packages [-f] [-d] [-e] [-s] [-3] [-i] [-u] [--user USER_ID] [FIL

TER]

pm list permission-groups

pm list permissions [-g] [-f] [-d] [-u] [GROUP]

pm list instrumentation [-f] [TARGET-PACKAGE]

pm list features

pm list libraries

pm list users

pm path PACKAGE

pm dump PACKAGE

pm install [-lrtsfd] [-i PACKAGE] [--user USER_ID] [PATH]

pm install-create [-lrtsfdp] [-i PACKAGE] [-S BYTES]

[--install-location 0/1/2]

[--force-uuid internal|UUID]

pm install-write [-S BYTES] SESSION_ID SPLIT_NAME [PATH]

pm install-commit SESSION_ID

pm install-abandon SESSION_ID

pm uninstall [-k] [--user USER_ID] PACKAGE

pm set-installer PACKAGE INSTALLER

pm move-package PACKAGE [internal|UUID]

pm move-primary-storage [internal|UUID]

pm clear [--user USER_ID] PACKAGE

pm enable [--user USER_ID] PACKAGE_OR_COMPONENT

pm disable [--user USER_ID] PACKAGE_OR_COMPONENT

pm disable-user [--user USER_ID] PACKAGE_OR_COMPONENT

pm disable-until-used [--user USER_ID] PACKAGE_OR_COMPONENT

pm hide [--user USER_ID] PACKAGE_OR_COMPONENT

pm unhide [--user USER_ID] PACKAGE_OR_COMPONENT

pm grant [--user USER_ID] PACKAGE PERMISSION

pm revoke [--user USER_ID] PACKAGE PERMISSION

pm reset-permissions

pm set-app-link [--user USER_ID] PACKAGE {always|ask|never|undefined}

pm get-app-link [--user USER_ID] PACKAGE

pm set-install-location [0/auto] [1/internal] [2/external]

pm get-install-location

pm set-permission-enforced PERMISSION [true|false]

pm trim-caches DESIRED_FREE_SPACE [internal|UUID]

pm create-user [--profileOf USER_ID] [--managed] USER_NAME

pm remove-user USER_ID

pm get-max-users

pm list packages: prints all packages, optionally only

those whose package name contains the text in FILTER. Options:

-f: see their associated file.

-d: filter to only show disbled packages.

-e: filter to only show enabled packages.

-s: filter to only show system packages.

-3: filter to only show third party packages.

-i: see the installer for the packages.

-u: also include uninstalled packages.

pm list permission-groups: prints all known permission groups.

pm list permissions: prints all known permissions, optionally only

those in GROUP. Options:

-g: organize by group.

-f: print all information.

-s: short summary.

-d: only list dangerous permissions.

-u: list only the permissions users will see.

pm list instrumentation: use to list all test packages; optionally

supply <TARGET-PACKAGE> to list the test packages for a particular

application. Options:

-f: list the .apk file for the test package.

pm list features: prints all features of the system.

pm list users: prints all users on the system.

pm path: print the path to the .apk of the given PACKAGE.

pm dump: print system state associated with the given PACKAGE.

pm install: install a single legacy package

pm install-create: create an install session

-l: forward lock application

-r: replace existing application

-t: allow test packages

-i: specify the installer package name

-s: install application on sdcard

-f: install application on internal flash

-d: allow version code downgrade

-p: partial application install

-g: grant all runtime permissions

-S: size in bytes of entire session

pm install-write: write a package into existing session; path may

be '-' to read from stdin

-S: size in bytes of package, required for stdin

pm install-commit: perform install of fully staged session

pm install-abandon: abandon session

pm set-installer: set installer package name

pm uninstall: removes a package from the system. Options:

-k: keep the data and cache directories around after package removal.

pm clear: deletes all data associated with a package.

pm enable, disable, disable-user, disable-until-used: these commands

change the enabled state of a given package or component (written

as "package/class").

pm grant, revoke: these commands either grant or revoke permissions

to apps. The permissions must be declared as used in the app's

manifest, be runtime permissions (protection level dangerous),

and the app targeting SDK greater than Lollipop MR1.

pm reset-permissions: revert all runtime permissions to their default state.

pm get-install-location: returns the current install location.

0 [auto]: Let system decide the best location

1 [internal]: Install on internal device storage

2 [external]: Install on external media

pm set-install-location: changes the default install location.

NOTE: this is only intended for debugging; using this can cause

applications to break and other undersireable behavior.

0 [auto]: Let system decide the best location

1 [internal]: Install on internal device storage

2 [external]: Install on external media

pm trim-caches: trim cache files to reach the given free space.

pm create-user: create a new user with the given USER_NAME,

printing the new user identifier of the user.

pm remove-user: remove the user with the given USER_IDENTIFIER,

deleting all data associated with that user

Although it's appear that the argument didn't work, on my phone I was able after that to change the language within the opened app :laugh: