Thanks for giving it a go! I can't express what a relief it is to hear a stranger say it feels professional and polished - until now I've been working on this by myself with only my own eyes and the occasional input from friends and family to measure it by, and I never felt satisfied beyond all doubt that I'd got it looking and feeling like a "real" game. Very glad to hear it meets the bar on that front.
On your specific thoughts:
1. I went and investigated Melvil, and I can't find any signs of him being bugged. Was the issue that you weren't able to play the follower onto the board at all? Or just that his play ability didn't activate as expected? If it's the former I suspect something just had you confused, maybe you didn't have enough money to play him and didn't notice - you can definitely play followers even if their play ability won't trigger, it won't have been that. But I did notice that if there's no target for the first part of his play ability, the "move a card in your hand" bit, then the second "draw a card" part won't activate either. Was that the issue, you played him as the last card in your hand and had expected him to draw a card for you? I might change it - I wouldn't exactly call it bugged as it is, it's fairly normal for card text on the same line to either trigger together or not at all, but on the other hand there's not much intuitive reason for the second part to be gated by the first like that, I can understand why you'd have been surprised. Worth thinking about, so thanks for putting it on my radar!
2. I do get what you mean (and I agree entirely about old Civs vs the latest one), but for this genre things are always going to be a hodgepodge (or ought to be, at least). Part of the fun of the game is looking over lots of different possible cards and identifying the ones that will synergise well with the rest of your deck, sometimes in ways that aren't obvious at first. If decks do end up being made up of cards with matching subject matter, it means the dev has railroaded you into specific "intended" combinations of cards and robbed you of the fun of looking for good mechanical synergies yourself. And honestly, I quite enjoy the aesthetic silliness of having bizarre combinations of cards working together in your deck.
3. I have had some vague ideas about it having some educational value for schools, but it's definitely not the primary target demographic for the game - more than anything I just want it to be a good TCG that appeals to people who like good TCGs. I went with the historical theme because an important part of any card game is interesting subject matter - most successful ones adapt a popular IP, and there are already tons of forgettable ones with generic puddle-deep slop-y fantasy settings, so why not something with endless material to adapt, plenty of good public domain imagery to draw on, and that everyone has at least some knowledge and interest in?
Thanks again for trying it out! I've given Inearth a go too, and I'll write up my thoughts for you later on today.