The books do mention seeing the AFTERFLASH of it though, but that would stem from bumping up any laser to the point it can slag away half a ton of armor in a single shot; energy levels at which you could hit the moon with ease for almost as much damage. At that point even the air along the path would provide sufficient diffusion, it might ionize, possibly releasing high level radiation in the X and K bands. There's a reason we can use lasers to easily split molecules and with quantum engineering even break atomic bonds.
ANY stray reflections even just from the air would most likely cause temporary (or even permanent) eye damage, which is why modern-times high power energy weapons are banned for ground target use.
(weapons that cause permanent blindness are banned by treaty -- with nations that honor them) What you might see isn't visible light, but damage to your retina or even macula from the radiation. Even non-visible light can cause blindness if it is strong enough. See "snow blindness' which is caused not by visible light, but by UV.
Reference for truthiness:
https://en.wikipedia.org/wiki/Photokeratitis
Just because you can't see it doesn't mean high levels of light energy cannot blind.
(sorry Spock, your second eyelid did jack, you're still blind!)
Which is why it's ALSO in the fiction that 'Mechs have filters for that
IF they even let you see out of the vehicle directly... which not all 'Mechs even do. Hence the really good 3d holography and circlevision strip... and why when some 'Mechs lose power in the fiction you'll see mention of the pilot "sitting there in the darkness" even though the fight is in the daytime.
If you can filter it, you can probably detect it, meaning you could probably draw it in the 3d render as a queue for the pilot. That's part of why I half expect that 'Mechs would basically have Geordi-vision. UV, IR, X, K, basically all forms of radio and light bandwidths, all able to be remapped into the visual spectrum as needed.