JR Bus Kanto to Kusatsu Onsen

I will be travelling to Kusatsu Onsen from Iiyama on 3 January 2019. According to Hyperdia, Limited Express Kusatsu 83 should depart from Takasaki Station at 12:33 p.m. and arrive at Naganohara-Kusatsuguchi Station at 1:43 p.m.

According to the JR Bus Kanto English website (http://www.jrbuskanto.co.jp.e.wn.hp.transer.com/bus_etc/cntimep01.cfm?... - albeit poorly translated) and Japanese timetable (http://www.jrbuskanto.co.jp/bus_route/pdf/j0450121_1.pdf), there is a bus that departs from Naganohara-Kusatsuguchi Station at 1:56 p.m. and arrives at Kusatsu Onsen at 2:18 p.m. However, based on the footnotes, it seems that buses won't be in operation on 3 January.

Is my understanding correct? If so, how should I make my way to Kusatsu Onsen from Naganohara-Kusatsuguchi Station on 3 January?

That bus is marked with a circle, which means it is runs only on the days when the Kusatsu train runs. So yes, it will run on Jan 3.