Good choice of speaker, congrats!
You seem to have three theoretical options:
A) Lower your ear height - now that’ll either need you to replace the sofa, or cut its feet - both undesirable options. And you don’t want to crouch either.
B) Increase tweeter height - you’d need to either get a taller stand made, or put raisers under the stand/speaker. The former will be extra cost and latter might affect the sound adversely. And 17 cm is too much to raise.
C) Tilt the speakers a wee bit upwards from the front edge so that the tweeters angle of firing ensures the sound hits you at ear height where you sit. If it’s only a few degrees, this may be the best option.
What’s your height? Because these are British speakers and stands and must have been designed for an average Brit male adult who is tall enough. (Unless I am wrong and they were primarily designed for the shorter Chinese customer). Have you checked if your sofa’s height is extraordinarily large? Like, how do shorter and younger people feel when they sit on it? Do their feet stay comfortably on the floor? If not, then in the long run you could contemplate changing/modifying it.
Also, not all speakers are so sensitive to exact tweeter-ear matching. Perhaps your previous speaker was. The Lintons may or may not be, you can find that out after you place them in the room and listen. Based on my audition memory of it and experience with Castle Knight (from the same manufacturer), the vertical dispersion may be good enough to not make the sweet spot too small.
However, the decision to buy them or not shouldn’t depend on this factor though as you can always go for the option C (immediately) or A (in long run).