Just a quick note.
"your ventilation system", fan and ducting seem to be bunched up? you lose about 45% efficiency of that fan every time there's a significant bend in the ducting.
* if you don't need the fan heat to keep your room warm? then why mount fan and filter inside the tent? I would pull air from outside tent and that small fan should be inside tent for circulation. You need only leave a port open to pull air through your tent that way.
*It's HARDER to start seedlings using a tent to control humidity but not impossible, you would need to add a humidifier and heat mat to add moisture and warmth at root level. Then dial in the amount of fan\ air flow needed to keep room temp correct. Dial in humidifier afterwards to get the increase in humidity 80%+ needed for seedlings and germination.
A slightly simpler way is to use a domed tray , low watt light and heat mat
Seedlings when grown indoors need to be started in a tray and dome with a heat mat to control medium temperature.
It's also a good idea to cover the propagation tray with a humidity dome and place the tray under low watt full-spectrum lights. The dome will keep the relative humidity in the propagation tray at about 98%—ideal for germinating seeds—and the full-spectrum lights will help keep the seedlings from "stretching" once they germinate.
Keep seedlings inside dome trays and on heated mat until they outgrow the tray. then they are ready or transplant to a container and medium of your choice