Complex sentence: It appears, however, that laryngeals left traces in Balto-Slavic: they triggered the "acute" register on a preceding vowel or sonorant diphthong, as an articulatory "residue".
Split into simpler sentences: It appears, however, that laryngeals did not disappear without a trace in Balto-Slavic. Instead, they triggered the "acute" register on a preceding vowel or sonorant diphthong, as an articulatory "residue".