-
That looks absolutely pin sharp! Very nice. I think your wall looks substantially more solid than mine. I'm worried that if I were to drill down only 120mm, mount the post and then lean on it to try to straighten it, there's a fair chance that I'd just tear the top 2 courses of bricks off. Having said that, there is one place that I can't get to the face of the wall easily as it's behind my shed, so I may try out that approach for that one post.
ffm-
I would be a bit more concerned about a single skin wall carrying the wind load, especially as it's a fence not a trellis but as you've already had a fence fitted it must be quite stable/sheltered.
When I fitted them I checked they were upright before/during the cement drying (which is very quick), if you've drilled larger holes than the threaded bar there's 10 degrees play. There's limited force involved in moving them 5 degrees or so to get them spot on once the trellis is going up.
Try it behind the shed and see how you get on.
Airhead
I was in the same situation, no experience of epoxy cement and no idea how effective the threaded rod would be. The rod had around 120mm going into the wall, so roughly 240mm long. The posts are around 800mm with trellis attached to the front, in a sheltered garden so wind is not a big factor.
You can get epoxy cement from Screwfix or similar, I think I used Fischer FIS VT VT Vinylester Chemical Mortar Resin. Something like 20 posts used 4 tubes. I didn't have to drill into the wooden posts, they were supplied drilled and epoxied in this case. I did buy a special brush to get the dust out of the holes in the cement/brick and hoovered the dust out, the posts are very solid and stable.
The result was much more solid than I had imagined, it's easy enough to straighten the posts and I've not seen them moving in the wind. I'd fretted about it because I don't normally do landscaping/gardening stuff and I'm used to high end joinery solutions so concrete and brick are a bit approximate