Ahh the filter setup and ducting looks good! Didn't know you actually had them operating.
Duct fan seem to have different speed options(?) I guess it's set to low if your RH tends to climb over 50% - So you should be able to set it in higher speed/to draw more.
You seem to have a big filter also so you need enough draw power through the filter to get the air to change in the tent properly! Your passive intake should work fine as long as you duct the exhaust air outside. As
@Azimuth said if you duct the air into the same room then you'll just recycle the hot moist air, not ditto.
Setting the duct fan on higher draw speed can and will reduse your tent temperature and humidity.
General rule is you'd want to change your tent volume (m3) x 3 times per hour.
Also if you open up a second tent flap for the passive intake then you double your intake capacity. Setting the duct fan on higher speed will also control the amount of passively intaken air. The more your exhaust duct fan draws the more it also passively draws air into the tent. This situation should create a nice little negative pressure inside the tent - which should make controling the environments esier.
They still would go for the next 14 days, easily.
Yellowing on the new growth is usually sign of a micro nutrient deficiency. Which is normal as they getting old. They might even turn into purple/pinkish.
- V