Day Trip to Takayama (from Kanazawa)

I plan to do a day trip to Takayama (from Kanazawa) on 14th Apr for the Spring Festival using JR pass.
Will the JR train be crowded with people leaving after the Spring Festival? There is a JR train scheduled at 8.50pm.
Do I need to reserve a seat for the train?
When and how can I reserve the seat?
Thank you in advance for helping me!
Joanne - Singapore

Yomatsuri, night festival, would last unitil 21:00.
http://kankou.city.takayama.lg.jp/_res/projects/kankou/_page_/002/001/...

With the train leaving from Takayama at 20:50, you will get to Toyama and Kanazawa at 23:01 and 23:35, respectively. The two trains up to Toyama are local trains, so you could not reserve a seat, even with the crowds. From Toyama to Kanazawa, you could reserve a seat. The duration is just 19 minutes at very late at night. I might think to skip the resevation, which would take some time to do. Anyway, you could do that at any JR stations while you are in Japan, such as the time you would activate the Japan Rail Pass, or while you are in Kanazawa or Takayama.
https://world.jorudan.co.jp/mln/en/japan-rail-pass/?p=0&from=Takayama&...

For another direction, there is an express train to Nagoya, departing at 20:44. Until then, there would be some more crowds in the station.
https://world.jorudan.co.jp/mln/en/?p=0&from=Takayama&to=Nagoya&date=0...

Hello Luisjp!
Thank you for your response & advise.
Have a good day!