Is there an easy and quick way to find the name of the current certificate holder of an aircraft in the IApproach software?

Yes.  The best way to search is to use the ‘Find by Model’ button (in the ADs section) and enter the desired aircraft model number. Once you have found the desired model and the AD search results are loaded, click on the TCDS button and the current Type Certificate will appear in a popup window. The Type Certificate will show the current TC holder.