Text placement and skipping of tied notes

not sure about tied notes but there's a boolean attribute autoplace you can use like:

var text = newElement(Element.STAFF_TEXT);
text.text = 'your text here'
text.autoplace = false

I guess it must be true by default.

For detecting/skipping notes based on ties, starting with 3.3:
/// Backward tie for this Note.
/// \since MuseScore 3.3
Q_PROPERTY(Ms::PluginAPI::Tie* tieBack READ tieBack)
/// Forward tie for this Note.
/// \since MuseScore 3.3
Q_PROPERTY(Ms::PluginAPI::Tie* tieForward READ tieForward)
/// The first note of a series of ties to this note.
/// This will return the calling note if there is not tieBack.
/// \since MuseScore 3.3
Q_PROPERTY(Ms::PluginAPI::Note* firstTiedNote READ firstTiedNote)
/// The last note of a series of ties to this note.
/// This will return the calling note if there is not tieForward.
/// \since MuseScore 3.3
Q_PROPERTY(Ms::PluginAPI::Note* lastTiedNote READ lastTiedNote)


If the text should be displayed below the staff, setting its placement property may be better than disabling autoplacement for it:
text.placement = Placement.BELOW

Actually I would recommend to set placement property correctly even if disabling autoplacement for an element, this can potentially make calculating positions easier and is generally more likely to work better across different scores and MuseScore versions. Still that is not strictly necessary.