In addition and without wanting to sound too cruel, but if your spoken English is anything like your written, you don't come close to having ICAO level 6 English.
I wouldn't blame the grading system too much. Never receiving a grade 5 (fail) is nothing to be proud about. A grade 4 is a fair and not sufficient to be put forward. On a bad day most guys probably get 3's. So if that's your best ever, then while it's minimum there's guys out there getting 2 or 1's every time with better CRM grades. It's been like this since before I upgraded 5 years ago.
While you might scrape minimum requirements, RYR doesn't have the time or energy to waist on someone who might pass when there's plenty who definitely will also waiting. In addition, the poster above is correct, why would a base captain stick their neck on the line for someone they aren't certain will pass. It'd only come back to them and their own skills at putting people forward would come into question. I wouldn't do it.