W3C and ontouchstart at mini-calendar-module

Hi there,

more and more customers want a page with 0 errors on a W3C base.

So - inspite of reaching that goal i got rid of almost every error caused by the mini-calendar.
But there are still two mistakes which are going way beyond my JS Knowledge...

The following "ontouchstart" isn't allowed at this point for HTML 5 sites.

So - is there a way to get rid of it? or to call a function instead of placing it directly here?

<img title="Vorheriger Monat" alt="Letzter Monat" class="mod_events_link" src="/images/pfeil-weiss-prev.svg" onmousedown="callNavigation('http://domainname.de/index.php?option=com_jevents&task=modcal.ajax&day=1&month=1&year=2018&modid=88&tmpl=component&catids=14');" ontouchstart="callNavigation('http://domainname.de/feg/index.php?option=com_jevents&task=modcal.ajax&day=1&month=1&year=2018&modid=88&tmpl=component&catids=14');">

Any hints on that?

Greets,
Thilo