Years ago I gave up fight over box 28 and line 130.
There was an attempt at reform between the T4 and T4A slips sometime around 2007-2008. While it helped clarify and standardize some boxes and types of income, it still left others out.
There seems to be no need to report T4A box 28 on T2125. The default position is line 130 unless you have a self-employed business.
Line 130 - Other kinds of income
Report the following income on line 130:
amounts received as an apprenticeship incentive or completion grant shown in box 130 of your T4A slips. For more information, visit Service Canada, see Guide P105, Students and Income Tax, or call 1-866-742-3644;
amounts distributed from a retirement compensation arrangement shown on your T4A-RCA slips (for more information, see the back of your slips);
training allowances or any other amount shown in box 028 of your T4A slips (other than amounts already noted for this line and lines 104, 115, and 125);
payments from a trust shown in box 26 of your T3 slips;
payments from a registered education savings plan (RESP) shown in box 040 (see line 418) or box 042 of your T4A slips;
annuity or registered retirement income fund (RRIF) payments if you are under 65 on December 31, 2017 and did not receive the amount because your spouse or common-law partner died (see line 115), shown in box 024, 133 or 194 of your T4A slips or boxes 16 or 20 of your T4RIF slips;
certain payments from a Tax-Free Savings Account (TFSA) shown in box 134 of your T4A slips;
designated benefits from a registered retirement income fund shown in box 22 of your T4RIF slips, or the registered pension plan amount shown in box 018 of your T4A slips. If you rolled over an amount to a registered disability savings plan (RDSP), see line 232 for information about the corresponding deduction. For more information, see Guide T4040, RRSPs and Other Registered Plans for Retirement;
amounts (grants) paid to you as a result of taking time away from work to cope with the death or disappearance of your child because of an offence or probable offence under the Criminal Code (shown in box 136 of your T4A slip);
PRPP income shown in box 194 of your T4A slips if you were under 65 years of age and you did not receive this income on the death of your spouse or common-law partner.
If there is an amount shown in box 18 or 22 see T4RIF slips.