Yes operates id say it appears to be a little dim inside but i havent used one before, and you are right it does appear to be some sort of adhesive my grief is ive never seen anyone elses with this or see it in any pictures online.
Yeah I don't think that is normal but I don't have that model so wait until someone who does chimes in. Where did you purchase it? As to it being dim those dual illuminated models are not as bright as the straight battery powered models in certain conditions.
I've got the rm08g on mine in sunlight its brighter than a red dot can get without the fuzziness.
Under shade its not as good as a red dot or or my accupoint when looking into bright.
At night its brighter than the tritium sights.
The liquid is the adhesive holding it all toegether. I got this model because it matches my acog and accupoint keeping the same reticle for all my main firearms. If the reticle is dim under some conditions that's why I have iron sights on it. It doesn't bother me since most of my shooting is under bright or night I'm seldom if ever shooting the handgun from dim to bright