I'd still say that motor needs to be outside. AND, your vent exit is too close to the window and garage door, easy for smoke & smells to drift in...

Here's my jerry-rigged setup, which exhausts the 2 C02 and 2 fiber lasers in my garage shop, 1 C02 and 1 fiber each share a blower, separated by Tees and blast gates to 'steer' the suction...
Outside the garage window is this 'patio box', which I semi-unearthed for these pics, which are pretty grainy as it's pretty dark out, no flash so I artifically lightened them up, but oh well!
blwrbox.jpg
--note the 2 intake hoses coming down out of the garage window... also notice the 4" hole on the front-right side of the box, there's another one on the left side under the tarp, those holes are right next to the blower's motors cooling-air intake, so the motors never overheat. (I just make sure the tarps are away from the holes a bit.) Inside the boxes I've stuffed fiberglass insulation around everything EXCEPT the blower's motor's proper, for sound abatement...--the exit hoses come out the left side, not seen in the photo above, curl around and run behind the box along the ground, about 15' away from the main box and into these home-made filter boxes, which are just storage boxes with a securely lockable lid--
chrcoalbox0.jpg
air is pushed into the boxes, and exits the other side thru a 4" hole- note the old furnace filter standing next to the right side of the boxes- That's just for good measure

INSIDE the boxes--
chrcoalbox.jpg
Is some 1/2" square hole wire screen to hold everything in, a basic furnace filter on the left side, again just for good measure, and the rest of the box is filled with one of the large bags of el-cheapo charcoal briquettes Walmart sells. Those briquettes ARE as grungy as they look, I need to change them out, they've done their job!

It's not perfect, but not once in 8 years has a neighbor complained, or even noticed (and I've asked!), the teensy bit of hum coming from both motors, even late at night (the fiberglass works), and more important, no one has ever said they've smelled anything. If you're standing right next to the charcoal boxes, you can sometimes see a bit of smoke, or smell the Rowmark or wood or whatever burning, but once you're 20 feet away, you can't see, hear, or smell anything- unless you're trying to!

My garage shop does smell of what the lasers are doing a bit, but it's never more than minor, the smell never ends up in the house, because any and all air moving thru the vents is in a vacuum condition, meaning all 'static' air in the garage is also in a vacuum condition, which removes air FROM the house, rather than pushing air INTO the house... And once the engraving stops, any leftover smells clear within a few minutes.