Your non-basic lands will be turned into Mountains or Swamps, depending on which Blood Moon you hacked.

The Blood Moons generate type-changing effects in layer 4 of the effect layer system.

613.1. The values of an object’s characteristics are determined by starting with the actual object. For a card, that means the values of the characteristics printed on that card. For a token or a copy of a spell or card, that means the values of the characteristics defined by the effect that created it. Then all applicable continuous effects are applied in a series of layers in the following order:

613.1d Layer 4: Type-changing effects are applied. These include effects that change an object’s card type, subtype, and/or supertype.

Magical Hack happens in layer 3, so it can’t interfere with the outcome.

When two effects in the same layer compete to do something, the latest of these effects wins.

613.3. Within layers 2–6, apply effects from characteristic-defining abilities first (see rule 604.3), then all other effects in timestamp order (see rule 613.7). Note that dependency may alter the order in which effects are applied within a layer. (See rule 613.8.)

613.7. Within a layer or sublayer, determining which order effects are applied in is usually done using a timestamp system. An effect with an earlier timestamp is applied before an effect with a later timestamp.

So if you hacked the first Blood Moon that entered the battlefield, then non-basic lands will be Mountains. If you hacked the second one, Swamps.