Kashubian language is used in northern parts of Poland. It belongs to West Slavic familly; its ISO 639 code is CSB. Kashubian locale based on a Polish one, differences are in: charatcers that kashubain use, names and abbr of days and months and yes/no expressions.
Created attachment 1182 [details] proposed locale
You shouldn't have actually copied the data for the unchanged categories into the locale file. Always use the copy instruction. I've changed the file and checked the result in.
csb_PL:week 7;19971201;4 csb_PL:first_weekday 2 looks suspicious: is your first day of the week really tuesday?
You are right, should be: "first_weekday 1", but unfortunately I'm not able to correct this now.
The base data is 19971130.