That's how you avoid a mountain, but not a tree. Teleporting into a tree would be 'not good'. Maybe the wormhole (or whatever) just bumps you a little to the side to avoid things like that, but I can't imagine they can pin the terrain down that precisely given that the potential landing place is the entire planet, for the entirety of time. (or at least several hundred years that we've seen). No way they've got it down that far; maybe you think it's a clear field but there was a sinkhole that spring that you missed. Something as simple as a fallen tree in the woods would be catastrophic when you appear partially inside it.
Dunno, they haven't gotten into the mechanics of it, but seems problematic. Easiest way would be for the machine to appear mid-air and be able to land itself safely, but nothing in the design or show itself would lend itself to that being the way it works. Having it pop back into place is ok as they know every micrometer of the facility, but pretty random going out in the world.
But they did wreck the landing facility a bit on the return, so there's at least some precedent for the time machine displacing whatever is in the way when it travels. It didn't replace the scaffolding, and it didn't merge with it, it pushed it out of the way/crushed it. Maybe it would just destroy the tree? What about a person walking in the woods? dunno if it would have the horsepower to displace, say, a solid enough object like a hill/dirt mound, mountainside, etc.
