Confidence is an estimate based on your recent answers - it's not a measure of your ability or potential.
Mastery means you've practiced a topic enough to know it well. But memory fades without review, so mastered topics may need occasional refreshers.
Progress bars show how much you've practiced, not how clever you are. Everyone learns at different speeds.
Some Latin forms have multiple correct analyses (like puellae, which could be genitive singular, dative singular, or nominative plural). If you give any valid answer, it counts.
This tool is for practice, not assessment. Use it to find what needs work, not to judge yourself.