The Celtic base-20 number system was also used in Gaulish and was adopted from that into French.

Gaelic counts in 20s too. I don't think there's any Celtic language that didn't use base-20 in some way. Some Teutonic languages (English, Danish) have irregular formations for 11-19 but they don't count in 20s beyond that.

Burushaski? geezabrek. Have you looked at Burushaski syntax? Not bloody likely.