Now that I've had a proper look, I find the 3rd set of holes (the lowest) are NOT top-link holes at all, so I only have 2 Cat 1 top link positions on the tractor. But I'm not complaining because, as tested, the 2nd (lower) top link position works much better with both box-blade and tipping link box for my purposes. (Obviously intended to test the forks as well, but just too tired at end of past couple of days work to be bothered - so fingers still crossed on that one.)
The 3rd (lowest) set of holes remain a mystery: measurement/closer inspection says they are circa 25mm diameter, but they won't accept a Cat 1/Cat2 converter sleeve (that I had to hand). And there is no way that any sort of pin could be inserted due to the config' of adjustable tow-hitch frame. I think they are just useless holes - in an idle moment I might ask Agromehanika why they bother to drill a set of holes that I can fit nothing into!
In passing: binding lift-link still binding on the thread: whether I can live with will depend on the cost of replacement. OEM offerings are limited so I shall have to seek Agromehanika price for replacement and consider!
Another passing thought: while 3PL Categories are deemed to be standardized, the only thing that seems to be standard is the size of pins!!