Hi,
Yes, you can do that too with the new PayPal Checkout plugin.
Regarding the issue with the old plugin, you can activate the debug setting of the payment plugin and next time you have the issue, you can look in the "payment log file" of the HikaShop configuration. It should contain information about what's going on.
But yes, switching to the new plugin will circumvent the problem, and not only that but the new plugin offers a better user experience for your customers. And that's without saying that the old plugin will probably not work anymore in a few years when PayPal discontinue the API since it's now almost 20 years old.