Common mistakes by native language
Japanese speakers
Mistake: Pronouncing every letter as "GURANDO PAA" with a full d release and epenthetic vowel.
Why: Katakana English preserves each consonant with a supporting vowel; "グランドパー" reinforces the two-syllable feel.
Fix: The d elides in the [nd + p] cluster: [ˈɡrænˈpɑː]. Or in fast speech, may further reduce to [ˈɡræmˈpɑː] with n → m assimilation before the bilabial p.
Korean speakers
Mistake: Producing clear released [d] and aspirated [pʰ].
Why: Korean releases word-internal stops audibly.
Fix: The d elides: [ˈɡrænˈpɑː]. And in casual American speech, the n often becomes m before the p: [ˈɡræmˈpɑː], giving "grampa".
Spanish speakers
Mistake: Producing Spanish rolled r, or preserving all consonants faithfully.
Why: Spanish preserves letters more; Spanish r is different.
Fix: English r in "grand" is [ɹ] (approximant, no tap). And elide the d: [ˈɡrænˈpɑː]. Common variant "grampa" [ˈɡræmˈpɑː] uses n → m assimilation.