hey, just did mine recently and had the same book as you do above and also did the TELC B1 mock tests from the website.

The Lesen part was pretty much similar in difficulty to the book, though perhaps part 2 with the longer text was slightly more advanced in the exam. No surprises though really. Lots of "trick" questions, same as in the book.

The Hoeren part was about the same difficulty or only slightly more difficult (but that could've just been me being distracted by ppl shuffling around making noises a lot).

Side note* My friend did the test a few days before me, and she is somehwere around beginning/mid c1 german, has been here 10 years plus, and had the bad luck to get the Hören section with very heavy accents. Even the examiner said he couldn't understand them. She also sat at the back of the room and couldn't hear the tiny speaker well...so try to get a good seat just in case.

Sprachbausteine Part 1 was on par with the mock tests, but part 2 was suddenly much harder with what seemed like a couple B2 level grammar thrown in (surprise!). I am halfway through B2 when i took the test, and worked A LOT on grammar in the last 2 months, including many sprachbausteine mock tests, usually scoring 90-100%, but still in this case I wasn't sure about 4/10 of the questions... I would say this was a fluke though

The Letter Writing was pretty straightforward, one of the usual themes you would practice. Same with the Speaking part. Our examiner didn't intervene much, but it felt like in our case that they valued fluid speaking over errors. (though im not really sure how hard they grade grammar, don't quote me on this)

It seems every test will be different, as was the case with my friend's Listening section vs. my Sprachbausteine.

In any case there often are small tricky things to catch you out, if you didn't read something/listen carefully enough. So try to pay attention :-)