I have sounds and quotes for most of the techs done (as well as changes to the appropriate files). The only ones I have not finished are ones that I think could use some tweaking such as the following:
Methane and vartech should be visible long before the ability to build sea colonies. This is true to life because we can find these resources even now with our technology without having a way to access them. I suggest making them available with robotics since submersible remote units are what we primarily use for making such discoveries. I am already making the changes in an extended version of this mod... don't worry, I will only submit it as a suggestion. You decide what things you want to keep.
Also, I suggest that you use different tech titles. Submarine exploitation... at least in english does not quite fit the concept IMO. I would call it something like ultrapressure engineering (for building the biodome/sea settler unit) and ultrapressure machinery for the sea mining facilities.
A third suggestion: It looks like you used a reskinned uranium for the methane. I suggest you use reskinned oil and call it "frozen" methane in the ocean. Methane as "natural gas" is available to us on land and you could use your current methane graphic as a land version called methane. Or you could simply call land methane "natural gas" and ocean methane "methane".
I am having difficulty finding a quote for one tech... but I can't remember at the moment which one it is. I will keep looking.
In my own version of this mod I have added 2 more techs in the industrial era:
Abolition (because emancipation came over 50 years after democracy), enables emancipation
Social Economics enables public education act (National wonder), library of congress (National wonder), public school (building), and urban planner (who works much like the one in CTP).
One more modern tech:
Asphalt enables distribution network (basically represents both our modern highways so it adds to road movement, and our trucking/distribution center network so it adds to merchant capabilities).
I am creating several different "releases" for my additions, depending on which features you want. Currently I have a raw "sound" update and then an update which includes all my bells and whistles that I have added. Finally, I may include one that reflects my ideas about the tech tree