Given
<translate>==test==</translate>
When rendered with the legacy parser, "test" is a heading (since the translate tags are stripped by the translate extension).
When rendered with Parsoid, we get
<p data-parsoid='{"dsr":[0,31,0,0]}'><meta typeof="mw:Annotation/translate" data-parsoid='{"dsr":[0,11,null,null]}' data-mw='{"rangeId":"mwa0","extendedRange":false,"wtOffsets":[0,11]}'/>==test==<meta typeof="mw:Annotation/translate/End" data-parsoid='{"dsr":[19,31,null,null]}' data-mw='{"wtOffsets":[19,31]}'/></p>in which ==test== is a paragraph.