In this episode, the Krill speak perfect English and all Ed and Gordon have to do is wear hologram suits. Their usual English works just fine, no "universal translator" suggested.

Who makes light fixtures that can withstand a large multiple of their regular power supply even for a few seconds? Do the designers thing "we better make these capable of killing ourselves, just in case?"

And after however long they've known the Krill planet is dark and such, nobody thought they might be sensitive to light until Ed had a flash of insight? Well, Kirk did the same thing often enough. Even about light. In "Operation: Annihilate!" nobody thought of the sun being BRIGHT until Kirk pressed a button on the little computer thing and it flashed at him.