So I looked and NEI (which is installed) is what has the light levels. Normally it's f7. You may need to go into the controls and see if it's conflicting with something else. If something else has f7 assigned you may need to unassign it for this to work.
Alternative: (warning, adjusting the mod list in sf3 may cause it to be unstable, might void the warranty, contribute to the rube Goldberg machine that creates the zombie apocalypse, might affect your tax refund and could result in weight loss, weight gain, nausea, loss of appetite, increase in appetite. Be warned)
You can manually add a separate mod yourself. If you're using the twitch launcher you have to click on the ellipse (three little dots) next to the get more content button and choose profile options. Then click the button that says lock profile to unlock it. It's locked by default. Click ok and then click get more content. You might have to refresh the list but once you do and it loads search for "light" and light level reloaded will pop up. Install that, could solve the issue. However, I don't know about compatibility so... got that going for you.
