This is an awesome Bot, even it's too good to be real.
But I have some bad news, this is not legal because it breaks some stake rules. There is a reason why they don't have the exchange/swap feature, and that's because they need a license to operate a service like that, but since that's not their business they will not implement it.
Now, the fact that you come as a third service provider with this service can make them close your accounts for breaking the Anti-Money Laundering and the Coin Mixing Policy and some other rules in their TOS:
7. DEPOSITS
7.5 You should only deposit money into Your account for the purpose of You using such money to place bets/wager on the Website. Stake is entitled to suspend or close Your account if we reasonably believe that You are depositing funds without any intention to place sporting and/or gaming wagers. In such circumstances we may also report this activity to relevant authorities.
7.12 Funds cannot be transferred from your Stake Account to the Stake Account of another Player.
8. WITHDRAWALS
8.3 All withdrawals must be done through the same payment method chosen by you when placing a deposit, unless we decide otherwise or are unable to do so. If you deposit using a number of payment methods, we reserve the right to split your withdrawal across such payment methods and process each part through the respective payment method at our discretion and in accordance with anti-money laundering policies and regulation.
16. FAIR USE
16.1 The Website and Services may only be used for recreational purposes by placing bets and wagers on events and/or gaming products.
17.4 You are not permitted to:
c) enter, access or attempt to enter or access or otherwise bypass Stake’s security system or interfere in any way (including but not limited to, robots or similar devices) with the products or the Website or attempt to make any modifications to the software and/or any features or components thereof;
I mean, i really like this service, and i think you should talk with Stake and wait for their approval before they decide to close down the operation. so, good luck with the service.