@ von Suppé
Yeah, an improved DirectShow subtitle preview would be great, or a better looking mpv preview that is smoother for my eyes.
When editing and syncing it gets tiresome after a while for my eyes, so the smoother the preview font style is the better.
So I'll stick to DirectShow for now.
I do much the same as you, starting with either an imported sup/sub/ or from scratch an srt.
When needed I create a BD sup where I can choose font, style, size, placement, color etc.
Without the excellent Subtitle Edit I would be lost!