Hi @Tobias_Hall, one thing I noticed, is that the bipolar.berlin site is not pointing at Webflow servers: Image 2017-07-17 at 3.23.36...
I would check that your fonts are loading correctly from the external server and that all font files were uploaded from the fonts folder that gets created at export: Code export | Webflow University
Also,you can tell if there is any issue with the font, or after export, by loading the exported index.html file that is generated, in Safari from the hard drive. The fonts should show correctly.
Webflow does not provide support for external server hosting, however the exports should be working fine on export. If there is any issue with the unmodified, exported site, contact to us on the support desk: Webflow Customer Support | Webflow University
I hope this helps!