The most accurate measure of short selling is the data reported by all broker-dealers to FINRA on a bi-weekly basis. These numbers reflect the total number of shares in the security sold short, i.e. the sum of all firm and customer accounts that have short positions. https://blog.otcmarkets.com/2018/11/13/understanding-short-sale-activity/
Are you saying that there is no way to actually track short interest? Or just that FINRA and OTC don't do it correctly?