while the fee from the tumbler is aprox 15 sat.
That means their transaction size is around 1000 bytes. If that's all there is, creating a new transaction for CPFP could work.
Current fees are rising again, you'll need to pay more than 100 sat/vbyte
on average to get it confirmed any time soon. That means paying about 0.001
BTC in fees
from one of the outputs of this transaction could work, but you'll need to count all unconfirmed bytes in your transaction chain to get a more accurate number.
If the sender has many more unconfirmed parents, it can get much more expensive.
I can choose to accelerate it thru mempool.space but will that even work?
Maybe. Maybe not. I haven't tried.
What do you think should i give it 1 more day or will this not show up to wallet "A" since it hasnt been confirmed over 2 days?
It doesn't look like 15 sat/vbyte is going to be enough any time soon.