Do your fonts include lowercase letters and full character sets?

Not always. Character support depends on the individual font and on the scope of that specific release. Some fonts may be intentionally limited, for aesthetic reasons or because they are meant to reproduce a very specific retro visual language. Others may include a broader set of characters. This means you should not automatically assume that every font includes lowercase letters, accented characters, symbols, punctuation, multilingual support, or a complete modern character set. If that matters for your project, always check the product page carefully and ask before purchasing. It is much better to verify that upfront than to buy a font expecting support it was never meant to include.