Yes, I can confirm that with the 4.15.0-9 kernel with which the touchscreen works, if I disconnect the keyboard dock I need to power cycle (not just reboot) the machine to get it back.
Dmesg for disconnecting and reconnecting the dock for the 4.15.0-9 and the old 4.12.0-13 (with which the touchscreen also worked, and does not lose the keyboard dock) attached.
Yes, I can confirm that with the 4.15.0-9 kernel with which the touchscreen works, if I disconnect the keyboard dock I need to power cycle (not just reboot) the machine to get it back.
Dmesg for disconnecting and reconnecting the dock for the 4.15.0-9 and the old 4.12.0-13 (with which the touchscreen also worked, and does not lose the keyboard dock) attached.