Good question. It seems that REAPER's built-in Properties dialog box for text events only applies to the first selected event, so it can't be used to change the text type of multiple events.
(Only text events with type "Lyrics" will show up in the notation view.)
The following quick script will change selected text events in the active take to lyrics:
Code:
take = reaper.MIDIEditor_GetTake(reaper.MIDIEditor_GetActive())
index = reaper.MIDI_EnumSelTextSysexEvts(take, -1)
while index > -1 do
_, _, _, _, texttype, _ = reaper.MIDI_GetTextSysexEvt(take, index, nil, nil, nil, 0, "")
if texttype == 1 then -- 1 = type "Text event"
reaper.MIDI_SetTextSysexEvt(take, index, nil, nil, nil, 5, "", true) -- 5 = type Lyrics
end
index = reaper.MIDI_EnumSelTextSysexEvts(take, index)
end
reaper.Undo_OnStateChange2(0, "Convert text events to lyrics")