You can add lemon juice to apple sauce or butter with no concerns about safety. It will make it more acidic, which is even safer than just the apples. Be sure to keep the butter hot, or bring it back to at least simmering before filling the hot jars. If allowed to cool, the processing time may not be enough to heat it through and it may mold, even if the jars seal.

https://nchfp.uga.edu/how/can_02/apple_butter.html 

We recommend against using electric multi-pots for canning, even boiling water bath products.  We have not seen good research indicating that they reach and maintain adequate internal temperatures that they heat up slowly enough for the contents of the jars to heat through before processing time starts. They also do not allow the cool-down time after processing is complete.  Until we are more certain of these products, we recommend caution.  This is of greatest concern for low-acid foods, but it may be a problem for fruits, too.