When implementing the ability for the camera to get into places (water/slime/lava/portals) with translucent surfaces, I’ve remembered that portals uses the same pointcontents value as water.
This means that in the case of portals, the chase camera will treat them as water, which means that when water is translucent the chase camera will go through portal surfaces, even if the portals aren’t translucent. And if water is opaque the camera will never go through portal surfaces, even if portals are translucent.
This can’t be fixed because it isn’t just an engine limitation. It’s also a tools limitation, because pointcontents are set by the map compiler, and therefore it’s also a limitation of all maps made for Quake.
There’s only other kind of surface that may have problems: Liquid surfaces whose texture name doesn’t begin with either *water, *slime, *lava or *portal. Such textures will only follow what’s set in the old r_wateralpha cvar, and their brushes will have the same pointcontents as water, but since r_water_blend_mode and r_water_blend_alpha doesn’t apply to them, they will have the same problem as portal surfaces. So, don’t worry if (e.g.) the chase camera go through an opaque liquid surface whose texture name begins with *ooze.
Other than those, the chase camera will always work perfectly with water, slime and lava now, and will only not go through them when they’re opaque.