Here is the info directly from the link you posted:
Bucket used General Purpose - 73-in. (1850 mm)
Bucket weight, lb. (kg) 392 (178)
Lift capacity at full height, lb. (kg) ---
Measured at pivot (U)
3133 (1424)
Measured at 500 mm ahead of pivot (V) ---
Measured at 800 mm ahead of pivot (V) 1956 (889)
Lift capacity at 59 in. (1500 mm), lb. (kg) ---
Measured at pivot (W) 4008 (1822)
Measured at 500 mm ahead of pivot (X) ---
Measured at 800 mm ahead of pivot (X) 2891 (1314)
Boom breakout force, lbf (kgf) ---
Measured at pivot (Y) 5378 (2439)
Measured at 500 mm ahead of pivot (Z) ---
Measured at 800 mm ahead of pivot (Z) 3604 (1635)
Bucket rollback force capacity, lbf (kgf) ---
At maximum height (VV) 3877 (1759)
At 59-in. (1500-mm) lift height (XX) 5544 (2515)
At ground level line (ZZ) 3860 (1751)
Also, Kubota does rate the loader lift capacity at 1500mm lift height (59") in addition to the full height spec. With that said, Kubota doesn't as readily post this info as Deere does. Some Kubota models they post this in the spec sheets, others you have to look in the owners manual. For example, they post the 1500mm specs for the
L4600,
L3800/3200, but I haven't seen it in the specs for the Grand L's or the Mx4700/5100.
Not trying to argue with you, just giving the OP another option.