Unfortunately there are no API endpoints for leaving comments on a KB's Feed, however there is a simpler way to notify someone when their articles are past their review dates.
You can create a KB report in TDNext that filters on the user in question being the owner of the report and looks for articles where the Review date is less than the run date plus 0 minutes. You might also add a filter for Review date is greater than or equal to a specific date of 1/1/2021 or the last month or whatever so you only get recent relevant results.
Once the report is filtered the way you want it to be, you can create a Delivery Schedule at the bottom of the Edit page for that report and assign it to deliver weekly or whatever to the person in question (configure to deliver only if there are results).
You could duplicate the report (or someone could copy it if they are doing this work themselves) and adjust the filtering so only the desired person's results are showing.