Is my bike safe to use if cogs and crank is not that aligned?
Derailleur bicycles are regularly ridden with more than twice the misalignment of what you have. They have to be ridden this way, because you can't fit N cogs into the space of 1 cog, well unless N=1. So some cogs have non-straight chainline.
Usually you can even backpedal these bikes with no ill effect.
If you have a chain tensioner, your bicycle differs from a derailleur bicycle only by having N=1. The only possible problem I see that if the chain tensioner does not have a clutch or the front chainwheel is not of the narrow-wide type, it's possible to drop the chain from the 38-tooth chainwheel.
So I'd classify it as safe. I'd not classify it as convenient (unless there's a clutch and narrow/wide chainwheel) since it's likely the chain drops someday forcing you to get your hands dirty in dirty black chain oil.