First off, what bark are you using?
Your pulls being tinted yellow or milky is perfectly normal. You'll get more yellow if you're extracting from Acacia vs. Mimosa. Milky means there's good stuff in there

The yellowing is just some plant oils/fats that are getting pulled by your solvent. As long as you don't get any of the basic mix in with your solvent pulls, you're fine.
It is worth it to get an air-tight container for freeze precipitation. I use this dish:

If the ambient temperature in your house is fairly warm (as it probably is during May or June) you'll get some condensation no matter what. As long as you can keep it out of the inside of the dish

I don't worry as much about condensation as I worry about all the stuff in my freezer being thrown away because it smells/tastes like naphtha lol.
One trick I use when taking the dish from the freezer is to pour off as much of the solvent as I can, then put the dish back in the freezer with the lid on for about 30 minutes or an hour, but on its side so the rest of the solvent runs down and I can easily pour what's left out of the corner before I put it in front of the fan.
And yes, if the smell of solvent is gone and you get only that new sneakers/floral kind of smell it should be fine, just use your best judgment.