Pension adjustment overcontribution?

This is an odd situation. My wife was on maternity leave all of 2019, but her employer said she can still contribute to her RPP (with cheques), and they will do their normal match. I though this was great since she had a large RRSP deduction limit/contribution room (they were equal) for 2019 as per her NOA for 2018.

So, her NOA for 2019 looks something like this (made up numbers but proportional to real):

• RRSP deduction limit for 2019 .........$100,000
• Minus: Allowable RRSP contributions deducted for 2019 .........$20,000 (this is from the RRSP contributions we made throughout 2019)
• Plus: 18% of 2019 earned income, up to a maximum of $27,230 ......... $2,000 (this was 18% of her mat leave top-up that she received through 2019)
• Minus: 2019 pension adjustment ..... $5,000 (this was the value of the cheques we wrote for the RPP contribution + match by her employer)
• RRSP deduction limit for 2020..... $80,000

So it seems like they calculated the RRSP deduction limit by subtracting the 2019 deduction from the 2019 deduction limit (i.e. $100,000-$20,000). Because the pension adjustment was greater than the 18% of the earned income, they did not factor this in the equation (i.e. I would of thought it'd be $100,000-$20,000+$2,000-$5,000=$77,000).

Furthermore, on the CRA website, under Calculation of 2020 RRSP deduction limit, Step 2: Calculation of additional deduction limit based on 2019, it says something like:

• 18% of 2019 earned income .... $2,000
• Minus 2019 pension adjustment ....$5000
• Equals Additional deduction limit based on 2019.... $0 (cannot be less than zero)

So, what gives? There are no statements in the NOA that an over-contribution was made, such as if your available contribution room is a negative amount. She works for a large company so I'm surprised they would be allowing mat leave RPP contributions via cheque at all (as you will always exceed the 18% earned income for the year).

Any help would be appreciated.