Hi,
Yes, you can. It’s a bit of a pain. I remember trying to use parms in my call to get this to work - there is one that supposedly works for this. Various people at various times gave ways that it worked, but it seems that with every update of Ajaxsearch, something becomes deprecated. Surprise! So that didn’t work for me.
And like you, I dug until I found that language file. But when you update MODx (or Ajaxsearch itself), and boom, your change in the language file is borked, so you have to go back in and change it again when your client says, "why did my Search change?"
There is a reliable way to do this, though, and it will survive an upgrade. You replace the default template for the search.
You’ll need to do some digging... check out the contents of this folder:
assets/snippets/ajaxSearch/templates/input.tpl.html
You can copy this code into a chunk, modify it, and then use this parm in your call:
&tplInput=`YourSearchChunkHere`
Another benefit of templating is that you can better control CSS styling of your forms, which is always a chore. I hope this saves you the time that I lost hunting this down.
Cheers, Dave