I have come across a couple of math articles published between 2005-2010 that have clear errors in them (the articles have a common author). Most of the errors are typos but a couple of errors, let's say, reinterpret basic theory. No erratum has been issued for the articles. The journals are peer reviewed (which is another story) but they are not from what one would call top-tier journals. However, I note that these articles have been, and continue to be, cited despite the errors - sometimes by articles in journals that are considered top-tier. In one case this has kept perpetuating a typo error in an equation. (It seems those citing the articles just accept what was written - again another story).
I have written to the author but no reply. The journal response was basically that unless the author wants to correct it, nothing much can be done. It was also said that as the articles were now 'old', correcting them was - in their words - not efficient.
My question is should I persist in having the errors corrected? Or do I just leave such errors to be repeated? I have considered writing a letter to the editor for publishing to highlight the errors - in the hope it will 'force' a correction the original articles (assuming the letter would be published). Ideas welcome.