segeln > segle
lesen > lest
Is the e changed from [e] to [ɛ]?
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The answer is no.
This may seem tricky to you because in words as der Rest, die Pest, das Fest there is indeed an ɛ.
BUT, as a basic rule, pronounciation of vowels in stems is stable in German, and if there ever is a vowel change, an Ablaut, this substantial change is marked by using a different vowel character/diphthong.
lesen → sie liest