The differences in the two transcriptions of the inscription suggest it is difficult to know exactly what this inscription said. I noticed the author in a footnote states his opinion that neither of the transcribers was reliable. Perhaps Sir Thomas and his wife built their tomb at the time they built the church but died later.
This IPM appears to suggest that Thomas was dead by 16 March 1396/7:
"William la Zouche of Haryngworth, Knight, contd. ... 733. Leicester. Inq. take at Leycestre, Friday after St Gregory, 20 Richard II. ... Cropston. Half a knight's fee, held by the heirs of Thomas Walsche, knight." CIPM, Richard II, vol. 17, p. 274.
This entry from Calendar of Close Rolls, Richard II, vol 5: 1392-1396 (1925), pp. 415-423,
www.british-history.ac.uk/report.aspx?compid=102264, suggests that Thomas was living in February 1394/5:
"1395
Feb. 15.
Westminster. ... Writ de expensis for 12l. 16s. in favour of ... knights ... at the parliament summoned at Westminster in the quinzaine of St. Hilary last, namely 4s. a day each for 32 days. ...
[Prynne, Parliamentary Writs, iv. p. 427.] ...
The following have like writs: ...
Leycestershire. Thomas Walshe knight and Nicholas Colman 10l. 8s. for 26 days."
And this entry (one of the items cited in footnote 5 in the HOP bio), from the same volume of Close Rolls (p. 212) suggests Thomas was living in April 1394 :
"1394 ...
April 10. Westminster. To Thomas Walsshe keeper of Leycestre castle, and to his lieutenant. Order by mainprise of Nicholas Munketon of Bukinghamshire, Thomas Mewe and Ralph Tuder of Kent and William Russell of Warwickshire to set free Thomas Virly of Leycestre, who is in custody in the castle prison it is said; as on his behalf it is shewn the king that he is by certain his enemies indicted for aiding and consenting to the manslaughter of Robert Burstall of Leycestre 'corviser,' slain by John Pykerynge of London 'vestementmakere' who is indicted and not yet convicted, and that he is ready after such conviction to answer for such aid and consent before the king or before the justices elsewhere at the king's command, and to stand to right in all things; and in the statute published at Westminster it is contained that persons indicted for aiding etc. are replevisable until the principals shall be convicted."