Belt length

When building the printer, you have to cut à 127 teeth , but we are at 63,3 cm

[i]Now from the end you just cut, measure the belt for 63.5 cm (25") or 127 teeth. This measurement is critical. We advise to count the teeth and also measure the distance before cutting.

The other half should be approx. 86 cm (33.9"). For this stage in the build we shall need the piece of 63.5 cm (25"). Store the piece of 86 cm (33.9") for later use[/i]
( Also, the total length belt is 3mm less tahn 63,5+86 cm)
Should I cut at 127 or 128 teeth ?

AFAIK do not cut at a teeth, but between teeths 127 and 128.
The size of second part of belt is not critical.