Based on my research I found out that if your qualification is BCS, BCA or anything which doesn't have engg word attached to it, then the certification requirement is CISP.
If the qualification is Engineering, then the certification requirement is APEGS.
The reason is Engineering jobs in Saskatchewan is regulated. I found this out while googling 2173 job positing based in Saskatchewan and in most of the postings licensing requirement from APEGS was mentioned.
The whole confusion is because two things clubbed together in NOC 2173 (Software Engineers and Designers) which has two things Software Engineers -> APEGS and Software Designers -> CISP
Why dont you try to get APEGS and file a new application.