Mnemonic can be support by a third package @conflux-dev/hdwallet, check SDK account doc HD wallet part for detail intro.
Check Error Handling for common errors and how to handle them.
If you are sending a transaction and it is not mined or it is timeout, you can check the following:
- The sending account have enough balance.
- If the transaction should be sponsored, the sponsor account have enough balance.
- The transaction nonce is correct(not bigger than sender account's nonce).
- If the network is busy, you can try to increase the gas price.
For more detail, check why tx is pending? and Transaction lifecycle for more info