Apply 4.3.5 Paypal To 4.1.5

Does anyone know if the 4.3.4 paypal addon can be applied to the 4.1.5 release and work properly?

I have a larger commercial customer who has intermittent paypal issues (described in more detail below).

However, they have no desire to attempt an upgrade at this time of year and so are kind of stuck where they are.

I was thinking that since paypal is an addon that I could (technically - I would not do without authorization from cs-cart) install the 4.3.4 version of paypal which I know has solved many paypal issues for my other customers.

So, would it work?

Details of what's happening.

2 payment methods:

1 - authorizenet_aim setup for US only

2 - paypal with no country specification

When a foreign (non US) customer goes through checkout, occasionally they select paypal and then when the order is submitted, authorizenet is used (instead of paypal) and it fails due to no credit card number, expiry, etc.

The customer never saw those fields and if they were presented, the cm-required micro-class would have prevented the form being submitted without data in those fields.

So if anyone knows a solution to the problem, I'm all ears. Or if you have tried using the current paypal addon on V4.1.5 with success, I'd be very interested to know that too.