PayPal's limitations and what PayPal does with the info matters to our cart, because we have to pass all the cart data to them in order for them to process the checkout payment, then afterwards they have to pass all that info back to us to confirm to our system that payment was good and completed successfully. If they can only handle 100 characters of text input per field and throw away any excess, then they will only have those 100 characters to pass back to us when they confirm the order. It would be impractical and hideously expensive for us (and thus also for you, as your subscription fees cover our costs) to store all pre-truncated cart data on our system and then re-add any missing data to the payment notifications we get from the processor.
To consider the whole process in real-world metaphors (bearing mind it doesn't literally work like this, but you may find it easier to understand this way):
* It's as if we hand out order-forms (cart instances) by the thousands every day;
* Only some of those forms come back to us filled out and ready to pay (going to Checkout);
* We copy the data from our order-form (cart) to another format that the buyer's chosen payment processor (e.g. PayPal) requires for checkout (every one of them is different), so we can send the order details off to them for payment;
* Some of their checkout forms only have so much room to write anything for certain lines of info, so we copy whatever we can fit in there and leave out the rest (which they'd ignore anyway);
* Then we send the completed checkout form off to the processor, who arranges for payment with the buyer independently of us;
* Every day, all day long, we get bunches of those order-checkout forms back from the various processors we handle, with a big, red rubber stamp on them that says PAID (they don't return any of the ones that were declined or abandoned by the buyer during checkout at all).
* We copy all the order data from those PAID checkout forms into a ledger (your E-junkie transaction log) and an invoice (sale notification email) that we mail to the seller, and we send the buyer a letter (thank-you email) to confirm their purchase and include any data products they purchased (codes or download links) that we can enclose in that letter.
* If we kept a copy of every order form (cart) we hand out, or even every order form (cart) that gets turned in (goes to checkout), we'd need a virtual warehouse full of filing cabinets and a huge clerical staff to match up original order forms with PAID checkout forms coming in -- and you would need to pay for all of that with inflated subscription fees -- instead of the simple clerical office and select clerks (e-junkie staff and software) that meets our (and your) needs currently.
As reasonably accurate as that description above may be for how things operate currently, we are working on a way to retain a copy of the complete product data from our cart temporarily for a brief period during checkout, so we can match up cart orders sent to checkout with any checkout payment confirmations coming back in. As usual, formal announcement of any new features or enhancements going live would be posted to our Service Status and Updates forum category here: