Thanks for the update. Haven't played the game for a while so really looking forward to the new disease challenge.
I think one idea for both slowing down, and maintaining the current speed is to have different tiers require different materials. So the lower tiers can still require dirt and water, but with middle tiers requiring materials such as gold and clay, and the higher tiers Wolframite and Phosphorus. Then maybe the highest tiers (assuming there will be more than four at some point) require materials that don't appear naturally and have to manufactured.
That way you can still complete the lowest tiers in the same timeframe as usual, while also making research a relevant part of the game well past cycle 20-30 because you'd first have to setup a fully functioning base before you could expand to / manufacture the materials for the higher tiers. Since at the moment research just isn't relevant past a certain point, and a point that is incredibly early in the game (compared to say reaching one of the edges, for example).
But then I was also under the impression (maybe mistakenly) that research is currently fast and trivial for a reason, that being to allow all players to easily play with and test all the buildings and mechanics in the game, which is pretty much essential for a game in the alpha stages of development both for feedback and bug testing. So personally I'm happy with quick and easy research at the moment for those reasons, although I would be quite disappointed if it remains in its current simplistic state for the final release (as then it would feel like a fairly pointless feature simply because of how bare bones and trivial the research system is) .