Hi,
So if I understand correctly, the issue is that the captcha from our ReCaptcha plugin generates an error when you try to register via that guest registration form, is that correct ?
In that case, I think the best is to add the line:
if (@$_REQUEST['option']=='com_hikashop' && @$_REQUEST['ctrl']=='user' && @$_REQUEST['task']=='guest_register') return true;
after the code:
if (@$_REQUEST['option']=='com_updateme' && @$_REQUEST['ctrl']=='subscription' && @$_REQUEST['task']=='api') return true;
(two places) in the file plugins/system/recaptcha2/recaptcha2.php
That will skip the captcha check on the guest registration form as it is not necessary since the customer already validated the captcha on the guest form of the checkout.
Auto-filling the fields of the registration form with the data from the guest user is not impossible, but would require quite a bit of coding compared to the modification I propose above.