19 minutes ago, Cusm said:

But in a card game anything besides the card in the sleeve is basically marking a card, and it makes since to not allow it. In X-Wing or Armada this is not an issue.

Like I said, not x Wing, but an easy rule to apply if they want.

6 minutes ago, Drasnighta said:

Like I said, not x Wing, but an easy rule to apply if they want.

Yeah, L5R is a different monster as a card game with random draw and you would be effectively marking a card by putting anything else in the sleeve. X-Wing would only have issue with that if you were sleeving and marking the damage deck.

X-Wing Tournament rules (Component Modifications, Lost and Damaged Components - Damaged Card) require that you have the original card available, however proxies of cards are allowed in the case of damaged cards. You need to keep the original card "near" you. Keeping the original upgrade or pilot card in the sleeve with the proxy would not be against the rules (that is"near"); as long as you are able to present the appropriate number of original cards needed on demand you should be good.