Your sure it's not pleked?
Yes, in fact i did not even know what pleked is until you asked me, but i checked on youtube and my guitar does not received this plek adjust
it is a headless guitar made with a simple overlord of music bridge that is a kind of steinberger bridge, was not expensive and the last owner did sanded the frets to avoid exchange some of then
this guitar has a Zero Fret instead of a nut, the frets are so wasted that the strings are almost inside of the frets, think it is time to exchange then
anyway,maybe there is no plek being made here at Brazil at all... my guitar had the frets sanded with a tool similar to this one that is used to check the height/level of the frets but instead has a blue sand paper glued to the tool
sometimes when the guitar`s neck is very well made the frets are large and there is no need to sand then but if the guitar`s neck is not so well build then you may need to sand to remove the buzz and get the benefit of the lower strings action, also if the guitar has a floyd rose for instance, and you try to low the bridge pivots and start to get more and more buzz, you try different strings, you try adjusting the trust rod, nothing works then this sanding can eliminate the buzz without having to raise the bridge again
i made this on a chinese replica that was good looking but terrible made and it worked well...