Subtitle brightness on HDR content

I’ve been comparing HDR and SDR sources of the same film on HDR and SDR displays, and have noticed that subtitles from the HDR source are too dark both when playing HDR natively or when being converted to an SDR display. I just noticed that the forced subs in Captain America Civil War looked darker than I thought they should be on my HDR display, in the UHD-sourced mkv. I compared with my blu-ray sourced mkv of the same film, and sure enough, the forced subs are much closer to white from the SDR source.

Unfortunately the screenshots from the UHD playback (either HDR native or SDR converted) are unusable, as the .png just shows image corruption (a Kodi bug?), so I can’t show just how much darker the forced subs are from the HDR source.

Is there anything that can be done to improve this?

Usually, users find subtitles are too bright on HDR and adjust the colour down to a grey shade.

Can you confirm how the OSD looks for you (HDR vs SDR). And remind us whether you are running kernel 4.9. Is this something new since the last update?

My subtitle display settings are all default. Both my Vero’s are on 4.9. I can’t say if this is a new issue as I have not owned an HDR display for that long, and recognised that SDR conversion of HDR content is work in progress. But I just happened to notice today how subdued the subtitles were from HDR sources (both on HDR display and when converted to SDR). As mentioned, the screenshots from the HDR source are unusable so I can’t show how much darker the subs are than for the native SDR source. This screenshot from the native SDR source shows a white level that is perfectly adequate, the HDR source has somewhat darker subs.

EDIT: I just popped the UHD disc into my Panny player, and it’s giving me white subtitles, unlike the much darker subs from the Vero.

EDIT2: sorry, I missed the OSD question. Playing HDR content on my Panny HDR TV, the OSD is a bit too bright, but the subs are dark. Playing the same HDR content on an SDR display, the OSD is now not as bright as native SDR, but again the subs are not white.