WP All Import and csv format

My product supplier has given me a csv with over 4000 products, all of which I have managed to import successfully.
However, there are many varied products with many variations for each and I can’t work out how the csv format can be amended to be suitable for WP All Import. The products change (by the hundred sometimes) on a weekly basis so I can’t go through each product changing the csv for each one’s attributes and variations.

So, how can I import something that on the csv in the attribute column that looks like this :
Size{2} : Large[18], Medium[17], Small[16] – so that it is converted into the accepted format for the attribute section in WP All Import? Obviously, in it’s present format, It won’t work.
Thanks in anticipation.

https://ww.wp.xz.cn/plugins/wp-all-import/