What you describe do not sound like bugs to me. The issues sound more like your project Theme and Master Slides have not been set up properly.
Button states can be very powerful, but if clicking on a button causes the text to be left justified, that would tend to indicate that the states have not been set up correctly. By default the Down state of any button is deliberately set to appear slightly smaller at runtime to give the effect of pressing the button. That may be what you are referring to. If you do not want that feedback change when clicked, you can remove the Down state.
Did you use the Master Slide layouts for quiz question slides to try and change the formatting of the buttons, or did you just do it on individual buttons on the resulting slides?
The Question X of Y caption that appears on quiz question templates can easily be made larger to avoid text wrapping. Just select the placeholder for it in the Master Slide and change it's width in the Properties tab > Options area.
I would also recommend you set up a number of custom object text styles that you can then apply to all objects that should share certain formatting (e.g. quiz question buttons). That will give you much better control over look-and-feel, plus it then allows you to change formatting for all objects attached to that style by just altering the settings in the object style.
If you haven't used Captivate since version 8, some of these features may be unknown to you. One caveat however is that the project you are currently creating in Captivate 2019 will not be transportable or updateable to Captivate 13. So, that may be something to consider.
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