My headphones are called "Kopfhörer" (German for headphones ;) and are listed as such in Bluetooth configuration:

$ hcitool name <address>
Kopfhörer

However, in PulseAudio they show up as "Kopfh rer" (with a space instead of the umlaut):

$pacmd list-sinks

  * index: 3
[...]
        driver: <module-bluez5-device.c>
        flags: HARDWARE DECIBEL_VOLUME LATENCY 
        state: RUNNING
[...]
        module: 30
        properties:
                bluetooth.protocol = "a2dp_sink"
                device.description = "Kopfh rer"
[...]
                device.api = "bluez"
                device.class = "sound"
                device.bus = "bluetooth"
                device.form_factor = "headphone"
[...]
                bluez.class = "0x240418"
                bluez.alias = "Kopfhörer"

Note how the "bluez.alias" is correct. This likely also affects other non-ascii characters.

$ pulseaudio --version
pulseaudio 8.0