Underlined part I found; It's actually initializing the tames to 0 and the wilds to startingKey and then adds some random number to all of them. The rest of the operations are a mystery I can't find. In particular I can't find the range subtracted/added to a kangaroo, or T-W.

Since there is no subtraction of the range present in the first place I think that's why there's no addition of the range back when a key is found. So the chance there's no "highest-but killing" operation that decreases intervals by 1 bit is still on the table.

Something else I discovered about this is that his Int class has 5 uint64_t elements, and the 5th one is only used if you overflow 256 bits by eg. adding two very large numbers, not that it'll ever be larger than 2^256 anyway because all of Jean_Luc's integer function calls are modulused by the secp256k1 group order. It basically means I don't have to worry about arithmetic on 256-bit (or 125/6 bit!) ranges that overflows