Thank you for this bug report. I tried with Windows and I reproduced the problem: when the drop-down menu is open, a click on an item always select the first item which is no loop. I write this for the next version. For now, you can use the arrows up and down from the keyboard to select the right element and then press "enter".
Regarding merging soundfonts together please have a look on this
page. With a drag and drop in the tree you can copy elements from one soundfont to another one.
Good to hear that the auto looping tool is efficient