Sighting is a different issue & not really fixable without a rework.
Cant swear by it but I think better vision capabilities as in 60 or 40 vs zero does give a very slight improvement. Probably & just going from something Ginger Tanker said TI is not as much as a benefit as it should be.
You could test I suppose by cloning units probably infantry so they are identical & fitting different vision aids if you really wanted to. Be hard to be conclusive though because what does it see better the unit, or just through the hindrance's like invisible dust etc.
Problem is only way to improve it AFAIK is to increase experience, so also evasion shooting etc.
So only simple
fix I can think of is different TI levels get an experience boost that applies only to the sighting routine.
By that as an example I mean a 40TI unit gets a built in experience boost of XX from the vision aid & it only applies to sighting.
If you wanted to could define systems a bit better this way so 40TI units as an example could come with 3 choices of experience boost to sight.
If you were going to do this though you would possibly want a big negative reduction if it was not through the front facing for most units to offset this so makes sneaking up on tanks still possible.