Regarding the Council of Constance in Switzerland, this is what I gleaned from an article by Caroline T. Marshall in the Lion History of Christianity (published 1997). She was writing about Jan Hus, who was ordained as a Catholic priest in 1401:
"His case was referred to Rome. In 1415 Hus attended the Council of
Constance in order to defend his beliefs... The Hussites, especially
after the execution of Jan Hus at the Council in 1415, held that all
Christians should receive both bread and wine. The Council prohibited
it. Wyclif was condemned for heresy by the Council in 1415, and his
body disinterred from holy ground in 1427." (pages 330-331)
Page 339 adds, "The two most troublesome movements [to the papacy]
were those instigated by Hus and by Wyclif, whose followers came to be
called Lollards. By the end of the Middle Ages they had come to attack
the very foundations of the medieval hierarchy, including the papacy
itself."
Another history book, "The Pilgrim Church" by E.H. Broadbent (Pickering Classic first published 1931, quoting from the 1985 edition page 124) notes,
"Another object of the Council was to combat the teachings associated
with the names of Wycliff and Hus... But, in spite of the Imperial
promise, [Huss] was seized and cast into a foul dungeon on in island
in the lake. To justify this action the Council promulgated a solemn
decree (1415), claimed as a decision given by the Holy Spirit and
infallible, for ever binding, that the Church is not bound to keep
faith with a heretic... After a solemn service of degradation, Huss
was burned."
I looked to a modern-day Catholic source to see if any mellowing of attitudes to such matters has occurred. In The Encyclopedia of Theology edited by Karl Rhaner (published 1981) it was written under the heading of 'Heresy I. Canon Law' that only a baptized Catholic who 'contumaciously denies or doubts a truth which ought to be adopted by virtue of divine or Catholic faith' can be called a heretic (page 604). It must be noted that Jan Hus was an ordained Catholic priest, and Wyclif was the best Catholic scholar in Oxford, and who considered preaching to be the most important duty of the clergy. He was a preacher. Both were accused of heresy.
Yet there have been changes in attitudes to heretics in more recent times. It further says on page 605,
"Vatican II avoided completely the words heresy and heretic. The
decrees speak only of separated non-Catholic Christians or of
separated brothers. In view of the Directorium Oecumenicum it may be
assumed that the notion of heresy and heretic have changed since
Vatican II. The view upheld by Augustine that those who are born
(Christians) outside the Catholic Church are not to be spoken of as
heretics seems to be prevailing once more. Hence the only heretics
would be those who deliberately departed from the doctrine of the
Church of Jesus Christ, and these would then be subject to the
penalties of canon law."
It seems clear from that that Hus and Wyclif are still viewed as heretics by the Catholic church for there was no retraction regarding their attacks on the foundational authority of the papacy. On page 608 Rhaner mentioned some ancient groups, but not the Lollards. He said, "The Church learns to know more clearly its own truth by hearing and rejecting contradiction of its own truth, and of its growing self-understanding."
The simple question that requires answering is this - Has the Catholic church changed its self-understanding of the authority of the papacy to come closer to that stated by Hus and Wyclif, or vice versa? The answer is, 'No. There has been no change in either stance regarding the authority of the papacy.' That is my answer to your main question.
As for your secondary questions about Catholic views regarding exhuming Wyclif's body in 1428 (44 years after his death), I can only point to a comment to your question, questioning details of the event. The exhumation itself is not denied. However, history records that at Lutterworth Church, around the grave, in the chancel, was Chichele, Archbishop of Canterbury, and Bishop Fleming of Lincoln, plus other dignitaries and clerics. The source I cite below adds that Wyclif's coffin was carried on the shoulders of men through the chancel, down the winding road to the River Swift. A fire was then kindled on the bridge; the bones of Wyclif were taken out of the coffin and flung into it. They were reduced to ashes which were then cast into the River Swift. Thomas Fuller, 'The Church History of Britain: From the Birth of Jesus Christ until the Year MDCXLVII, 3 vols. (London, England: Thomas Tegg and Son, 1837), 1.493
