Man pages matching name qwttextengine in section 3:

QwtTextEngine.3.en	debian 10 / libqwt-doc
QwtTextEngine.3.en	debian 10 / libqwt5-doc
QwtTextEngine.3.en	debian 11 / libqwt-doc
QwtTextEngine.3.en	debian 12 / libqwt-doc