A common example of "extranjerismo no adaptado" is
pitsa. Less common are such as
élite, which, depending on the region, can be pronounced more or less like the original word (Argentina), or literally read as if they were Spanish words (Spain).
Some very slight heteronyms are created by the new graphical stress rules, which don't distinguish between diphthongs and hiatuses. For example,
/pi'e/: I tweeted or chirped.
Given the prevalence of English in commerce, there are some "extranjerismos" which share their spelling with a native word, but they aren't generally used in common speech.
One example is "SALE".
/sejl/ - sale,
/'sale/ - he/she/it goes out.
I'll add some more if I think of them.