You shouldn’t have any problems from a slightly compressed load.
There are many professionally developed loads that are compressed.
What you really don’t want in a smokeless load is that the load density is so reduced that you can get ignition across the top of the powder for the length of the case. Pressures can go up markedly in that instance.
Then how do you load a light target load? With a .38 and a 148 grain wad cutter, you only need 2.7 grains of Bullseye. That's about a third of the case volume.
Usually, if you're compacting the powder, you've accidently double charged the case, and it will go boom. If you're working up a compressed load intentionally, that's a different matter.