Not sure what is confusing you. If the cash paid is classed as a CG then it be reported on one's T3 slip so there's really nothing to do, beyond waiting for the T3 slip. Same for the RoC.... This is why I find this stuff complicated. You have to make sure that you find figures for the Reinvested Distribution.
Where one wants to spot check, pick a simple year and compare your numbers against the T3 slip.
For the phantom distributions, find whatever method you prefer for getting the phantom distribution numbers. Most ETF vendors I have checked publish it multiple ways, in addition to the CDS Innovations web site.
I used to think that as well but someone replied to my post showing how to get the annual reinvested amounts off the particular ETF's web page. I'll have to find that post again as I don't recall the details and when I tried to retrieve it I seem to be overlooking the spot, just like was I was before .... For iShares however, the [phantom] distributions part of the web site doesn't show it. Instead you have to download the special PDF file they publish on tax characteristics each year.
When my ETFs have to go into the non-registered account, I plan to spot check them every year or two ... the same as I am doing now for the REIT ACB.... I flip flop between thinking I should calculate it all (as I wrote above) and just using TD's book value. So far, the book values I've seen appear to be perfectly good.
I expect it will be fine as I see the phantom distribution detail line items and RoC ones in my registered accounts, each year.
I think you are confusing yourself....I'm still confused about the whole thing. Capital gains distributions are not the same as reinvested distributions; the reinvested distributions are often hard to find; and ROC is paid along with each quarterly distribution so if you've placed trades in the year, everything gets more complicated. The T3 helps, but overall, I find the whole process very confusing.
If you trust the T3 then it reports the CG in box 21 and the RoC in box 42. The issue I see if the broker rolls up multiple investments, making one check the detailed summary that is also provided. It will be more difficult to spot check where one has bought/sold as one will need a version that breaks it down by payment, which CDS Innovations covers.
The phantom distributions are once a year so the buying/selling won't matter as long as you know the number of units in mid Dec. Once you know what term the ETF provider likes for phantom distributions, is it that hard to google "2020" ETF provider "phantom distribution name of choice"?