incorrect font display

please have a look at www.beamtenberatung.info
There is a custom font 'Alwyn New' installed.
I add at Custom CSS in MAXIMENU CK:

font-family: 'Alwyn New' !important;

i have testet with Firefox, Google Chrome, Opera and Edge at Windows and it works well.
My client uses Safari and sends me a screen that looks different
What is the problem?

Hi
this is not related to Maximenu CK
this is related to the font itself, you must check that it is compatible with the Apple devices. There many threads on Google about Safari/Apple and such problems
how are you loading the font itself ? (because here you are only setting a CSS property, not loading the font file)
CEd

but why is it possible that some font in Safari is displayed correctly (f.e. the E-Mail top right) and in the same display the Menu have other font displayed?

I'm not a font manager
I don't know, you shall check on Google, by my side in Maximenu CK I use the google font code to load it, nothing less, nothing more
this is really not related to Maximenu CK and I'm sorry to tell you that I have no idea why you have this problem on Safari, but this is related to Safari itself