Hey there, not sure if you’re still looking for a solution, but the reason you’re getting that error is likely because the code you came across was designed for an older version of RSCSV. The author has since then updated the plugin’s save function, and so the old code won’t work.
I was in the same position as you today, looking at both of those posts and trying to figure out a solution. I eventually created this, with the help of certainlyakey’s code you linked to. It should work using this CSV.