Understand the code and try the Bitrix script

There is a self-written script for importing data from the excel file into the catalog and properties of the Bitrix product.
It is necessary to understand the code and understand why the properties of goods are not cleaned before importing (now they are being added, although there is a button for cleaning properties)
changes were made in the file to speed up the speed of import, apparently some of the code was erased, there is an old version of this file, but for some reason it also does not work.
It is necessary to understand and make one working file out of two, or to add cleaning of product properties in the current version