Transition tiles wood look - wooden floor

That can be easily circumvented by deliberately choosing a clearly different tone; possibly also changing the direction of the pile. My bigger concerns would be 1. the buildup heights of both coverings and 2. the dimensional accuracies of all "participants" at the transition (profile). Maybe can clarify this?

But isn't that the case with all transitions from the bathroom to the hallway and manageable there as well? In this respect, I actually have no concerns, because almost no one has a continuous floor covering in all rooms.

Concerns that the transition then looks like it was done intentionally but poorly because the wood colors clash.

I agree with your concerns 100%.

In the hallway downstairs we have black and white checkered tiles and parquet in the living room... The transition is also not "intentionally poor".

In this example, nothing clashes. But with wood and wood. It doesn't matter whether there are tiles in the bathroom and wood in the hallway – it's about wood next to wood, which is either only similar in texture, only similar in color, or similar in grain. This "similar" is "cheap". Take a contrast in the bathroom... there are so many great tiles, wood grain is slowly going out of fashion.

We definitely won’t match the exact shade of the tiles with the wooden floor and are now worried that the transition will look intentional but poorly done, because the wood colors clash.

These concerns are justified. Besides the color, you also have a tactile transition that cannot be avoided. You can make that visible without creating a huge contrast.

My son insisted on wood-look tiles in his bathroom and I was persuaded—after all, it’s his apartment. What always bothers me there (just like with laminate and vinyl) are two things that immediately reveal the fake:

[*]The repetition rate of the grain—I’m so crazy that I notice the repeating patterns within seconds.
[*]The "miscommunication" of the sense of touch and smell.

(With the kitchen countertop, I also accepted the fake since the overall kitchen package makes sense to me. But admittedly, I am not fully at ease with it either.)

Take a contrast in the bathroom... there are so many great tiles, wood texture is slowly going out of fashion.

We have been going back and forth a lot, but unfortunately we don’t like that much in terms of tiles. I find gray concrete look throughout the bathroom quite cool and monotonous. Sand-colored tiles are warmer, but I don’t find them particularly modern. Very trendy are strongly patterned small tiles (e.g. in Portuguese style), at least in some accent spots, but that’s too fashionable for me and my husband has vetoed it.
Since our bathroom is only 8 sqm, the tiles shouldn’t be too dark either. Wood-look floor tiles with wall tiles in light gray concrete look, plus a white washbasin with a wood countertop, has been the best solution for us so far for a bathroom with a bright, cozy and still quite modern appearance. But maybe we’re overlooking some other great trend...

What always bothers me (just like with laminate and vinyl) are two things that immediately reveal the fake:

[*]The repetition rate of the grain – I’m so crazy that I see the repeating patterns within the first seconds.
[*]The “miscommunication” of touch and sense of smell.

I fully agree with you that you don’t get tempted to confuse fake wood surfaces with real wood. With vinyl and laminate, however, you mostly still have the alternative of real wood – for me it would therefore never be an option to take wood-look tiles in the living room, because it simply doesn’t look like parquet. In the bathroom, however, you don’t have a real wood alternative, although I can understand if one then doesn’t like it and rather resorts to “real” tiles.
Was the transition to the adjoining room successful with your son?

Sand-colored tiles are indeed warmer, but I don’t find them particularly modern.

Well, beige and natural have long since replaced the grey trend ;)

But maybe we’re overlooking some other great trend...

Set your own trend!
Think again about the monotonous light grey on the walls, ...(your own quote:)

but unfortunately we don’t quite like so much grey tile-wise, overall the concrete look in the bathroom seems pretty cool and monotonous to me.

... and mix things up. There are so many other options for the walls right now that have outlasted trends.

If the bathroom is only 8 sqm, then I would recommend something light and subtle on the walls, and something more durable on the floor, maybe sandstone-colored, which then extends up to the shower or something like that.
Retro tiles on the walls, for example, play with shape, while the color remains rather understated.

Go to [schöner Wohnen] on bathroom tiles.. there is the whole range, and wood look and gray come up very, very briefly ;)