[Renate]

For your reference, here is the HID report descriptor for this beast.
You can see that it's a keyboard, digitizer and consumer control.
With "29 65 Usage maximum (Keyboard application)" they have declared themselves a full keyboard.

Spoiler:

05 01    Usage page (Desktop)
09 06    Usage (Keyboard)
a1 01    Collection (Application)

85 01    Report id (1)

75 01    Report size (1)
95 08    Report count (8)
05 07    Usage page (Keyboard)
19 e0    Usage minimum (Keyboard left control)
29 e7    Usage maximum (Keyboard right GUI)
15 00    Logical minimum (0)
25 01    Logical maximum (1)
81 02    Input (Variable, Absolute)

95 01    Report count (1)
75 08    Report size (8)
81 01    Input (Constant)

95 05    Report count (5)
75 01    Report size (1)
05 08    Usage page (LEDs)
19 01    Usage minimum (Num lock)
29 05    Usage maximum (Kana)
91 02    Output (Variable, Absolute)

95 01    Report count (1)
75 03    Report size (3)
91 01    Output (Constant)

95 06    Report count (6)
75 08    Report size (8)
15 00    Logical minimum (0)
25 65    Logical maximum (101)
05 07    Usage page (Keyboard)
19 00    Usage minimum (Keyboard no event)
29 65    Usage maximum (Keyboard application)
81 00    Input (Array, Absolute)

c0       End collection

05 0d    Usage page (Digitizer)
09 01    Usage (Digitizer)
a1 01    Collection (Application)

85 03    Report id (3)

09 22    Usage (Finger)
a1 02    Collection (Logical)

09 42    Usage (Tip switch)
15 00    Logical minimum (0)
25 01    Logical maximum (1)
75 01    Report size (1)
95 01    Report count (1)
81 02    Input (Variable, Absolute)

09 32    Usage (In range)
81 02    Input (Variable, Absolute)

95 06    Report count (6)
81 03    Input (Constant)

05 01    Usage page (Desktop)
16 00 00 Logical minimum (0)
26 e8 03 Logical maximum (1000)
75 0c    Report size (12)
55 00    Unit exponent (0)
65 00    Unit (0)
09 30    Usage (X)
36 00 00 Physical minimum (0)
46 e8 03 Physical maximum (1000)
95 01    Report count (1)
81 02    Input (Variable, Absolute)

26 dc 05 Logical maximum (1500)
46 dc 05 Physical maximum (1500)
09 31    Usage (Y)
81 02    Input (Variable, Absolute)

c0       End collection
c0       End collection

05 0c    Usage page (Consumer)
09 01    Usage (Consumer control)
a1 01    Collection (Application)

85 04    Report id (4)

15 00    Logical minimum (0)
25 01    Logical maximum (1)
75 01    Report size (1)
95 16    Report count (22)
0a b1 01 Usage (AL Screen saver)
0a 23 02 Usage (AC Home)
0a ae 01 Usage (AL Keyboard layout)
0a 8a 01 Usage (AL Email reader)
09 40    Usage (Menu)
09 cc    Usage (Stop/Eject)
0a 21 02 Usage (AC Search)
09 b6    Usage (Scan previous track)
09 cd    Usage (Play/Pause)
09 b5    Usage (Scan next track)
09 e2    Usage (Mute)
09 ea    Usage (Volume decrement)
09 e9    Usage (Volume increment)
09 30    Usage (Power)
0a 83 01 Usage (AL consumer control configuration)
0a c0 01 Usage (AL Entertainment browser)
0a 07 03 Usage (775)
0a 08 03 Usage (776)
0a 01 03 Usage (769)
0a 9e 01 Usage (AL Terminal lock)
0a 24 02 Usage (AC Back)
09 70    Usage (Display brightness decrement)
81 02    Input (Variable, Absolute)

95 01    Report count (1)
75 02    Report size (2)
81 03    Input (Constant)

c0       End collection

This is from the Bluetooth HCI snoop in Developer Settings.
You have to enable it, then reboot.
The log is found in /data/misc/bluetooth/logs/btsnoop_hci.log