Hi @idefix37, I'll try to answer as many of your questions as possible.
This is what airport station detail looks like in my browser (chrome-based)
The column graph seems to display the precipitation amounts, but there is no scale when it is an airport wheater station
True, hovering over the time of observation shows all its values in the info window above the chart. In my screenshot, it shows 3mm
What is the meaning of the letters like +SHRA, RA, ...
Those are weather phenomena codes used in METARs, for example. See more info here. The info window above the chart "translates" the code to human readable form, in my example +RA
is Observed weather: heavy rain
.
What is the meaning of the blue colour and the purple colour?
I believe it is the same as in meteogram (blue rain, purple snow), but I might be wrong.
Shouldn’t the Rain and the Pressure lines be interchanged?
Most likely yes. I'll raise this question further.
A word is missing : Flight rules and ….?
Looks like some alignment/crop issue. My screenshot shows Flight rules and visibility
. Are you perhaps using zoom in the browser other than 100%?
What is the meaning of the 3 small vertical bars
Again most likely cropped letter m
(meters) that shows in my screenshot correctly.