Forgive me if there's a setting and I've overlooked it, but I almost swear it used to be in an older version. We allow PVP within the bubble, but during the week the server runs in PvE until Purge on Saturdays. If you're outside of the bubble, the delineation is very clear, but once inside it's difficult to see where the line is. Is there, or can there be a way to slightly darken the bubble so that it's easily visible from both sides?

you can increase Create Dome Around Event Using Spheres in the profiles

We have that set to recommended

"Create Dome Around Event Using Spheres (0 = disabled, recommended = 5)": 5,​

If I increase that value, it will make the bubble become more opaque?

yes, the bubble is spheres