Congrats on achieving a functional governance proposal which will be the envy of most games/ organisation, looking forward to see more in coming future.
My view on this proposal is like tcg shop owner facing issue on proxy cards at ALL events.
Maybe the underlying problem is rental/delagation itself. The low cool time makes it easy to spam temp ownership at multiple accounts, hence any extra reward cards those account acquired will be sold cause there's no usage. I presume passionate players will keep their current reward cards(at least 3 of them) vs farmers ( maybe a pelacor bandit only)..thus I like to suggest :
(A) I would like dev look into possibity of Staking reward cards base on rank for everyone wanting to Continue earning. ( just like land uses creature to produce items, reward cards be used to generate earnings).
Example : Silver rank need lvl 5 common staked, Gold need lvl 8 common staked, Diamond lvl 9 common, champion lvl 10 common staked.
( initial idea is every splinter should stake 1 card base on rank to earn reward: 6 splinter to stake and neutral card act as joker / replacement).. For each missing stake card, deduction of reward be implement like 16.67%
(B.) Rented/delageted card may need to increase cooling time if (A) were to implement. ( to prevent multi account usage of same card on same day). Dev may make un staked cards usable after 1 month ( like sps un stake), but that's going overboard.
Just my simple thoughts.