I know abot lipase, but I need researchings and yieldings about enzymatic transesterification

All sites I’ve visited seem to show exactly the same result: a long-chain fatty acid with a carboxylate salt at the end! But I know this can’t be true, since you can’t run diesel engines on soap! Can anyone clarify the difference?
Specifically, base (NaOH) catalyzed transesterification

Is it recommended to mix more than one type of oil (i.e. canola oil and soybean oil) before transesterification to produce biodiesel? If not, why not, exactly? If so, what considerations need to be made?

Is it recommended to mix more than one type of oil (i.e. canola oil and soybean oil) before transesterification to produce biodiesel? If not, why not, exactly? If so, what considerations need to be made?