Alex and the Ironic Gentleman is a quirky adventure of the punny, tongue-in-cheek, intentionally (and intensively) whimsical sort. The Ransomed Crown is the fourth book in the Saga of Roland Innes, which is set very much alongside the legend of Robin Hood. And The Case of the Peculiar Pink Fan is fourth installment in the Enola Holmes mystery series (which I wholeheartedly adored and cannot recommend more).
C. J. Milbrandt 
The cover and your description (intensively whimsical) of Alex and the Ironic Gentleman made me think of Brandon Sandarson’s Alcatraz vs the Evil Librarians books, where members of a family have super talents like “running late,” “falling,” and “breaking things,” which make them quite the force. Have you read them? https://brandonsanderson.com/books/alcatraz/alcatraz-vs-the-evil-librarians/
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