Can't find Sort options in Numbers.app

A CSV file is an array of text. Each line in the CSV is a row of data in a spreadsheet, with commas separating the data/columns for that row. There is no interpretation of whether it should be the other way around. That's what it is.

You can select the table and use the menu item Table->Transpose Rows and Columns to swap your rows and columns after import.

There is no horizontal sorting. Sorting is vertical only.

Will you share a sample of the data so we can look at your situation more specifically.

Without that I can suggest that, since Numbers does allow you to transpose the table (swap the rows and columns). If you did perform a transpose action, you would be able to sort the rows (that were columns).

Number does what it does. You are conversing with fellow users.

If you want to provide feedback to Apple, you may use the Numbers menu item "Numbers > Provide Numbers Feedback"

TMSea, many if not most spreadsheets/tables are similar to databases where each row is a record in the database. Each column is for a specific piece of data like first name, last name, and adddress, or credit, debit, balance. Sorting across rows horizontally would totally destroy the spreadsheet/table. This may be why horizontal sorting is not an implemented feature.

Apps to not tell you why they do not have an infinite list of features. Help for an app will tell you how to do what the app CAN do.