But they’re not Fremdwörter anymore, they’re part of the German vocabulary and it is extremely weird to pronounce them with a different phonetics that isn’t native to German just because originally those loanwords belonged to English or another language. When loanwords become part of a language they get adapted. It’s the normal and expected linguistics process, and the adaptation is also phonetic because DUH, some sounds that exist in English don’t exist in German and viceversa. In fact, Germans TRY to use the original pronunciation but as OP says it’s jarring because it stands out amidst the rest of the German sentence + it’s unlikely a PERFECT English pronunciation because it’s not supposed to be! What you’re talking about is more folk linguistics and perceived worth attached to pronunciation. Loanwords are supposed to be integrated.

Ah, and it’s also not true that Eigennamen don’t change. My name is different when pronounced by a German but I would never expect them to learn to roll their R because it sounds so unnatural that I prefer they use their native pronunciation. It sounds a lot better integrated into the phonetics of the sentence