Non native English teachers accents are a little strange
Teachers who are not native have some bad habits with their accent
癖がある - habit, bad habit, strange
癖がある発音をする - bad habits with accents, strange accent
母語ではない - non native
Non native teacher, teacher who is not native
Non native English teachers accents are a little strange
Teachers who are not native have some bad habits with their accents
Most teachers whose mother tongue is not English have some kind of an accent when they speak English.
この場合、次のような言い方ができますよ。
ーMost teachers whose mother tongue is not English have some kind of an accent when they speak English.
「母国語が英語でない先生の多くは、英語を話す時に何らかのアクセントがある]
mother tongue「母語」
to have some kind of an accent when they speak English「英語を話す時に、何らかのアクセントがある」＝「発音に癖がある」
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イギリス 
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