But if I do manage to create this modcomp I might make it modular so that everyone can easily use it.
The concept of
"Modular Mods" - meaning that it is possible to load multiple mods simultaneously -
does not exist in Civ4BTS or Civ4Col.
You will always need to
merge the mods
in some way. (Some files will always need to be merged manually.)
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Depending how well
you encapsulate your logic into separate files, this might be easier or harder.
Also
depending on the other modders skills merging specific things like C++, Python or XML is easier or harder.
For most people:
- Merging XML --> really easy
- Merging Python --> a bit of try and error (easy copy paste but errors are difficult to spot)
- Merging C++ for DLL --> quite hard (at first complicated but errors are really easy to find)
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The only real
advantage for merging you will get with
"pure Python" is, that other modders will
not need to re-compile a DLL.
The other advantage
"pure Python" has, is that it will also
work on MAC OS.
Python also
has disadvantages though. It is much
more difficult to write really complex and powerful code in Python than in C++.
(It is much more prone to errors because debugging and IDE support for coding are less existent.)
IDEs for C++ usually slap any obvious errors directly in your face.

Only the really tricky stuff might need test games with debugging.
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Summary:
Real "Modular Mods" is not possible for Civ4BTS or Civ4Col. Some merging is always necessary.
But yes, Python is usually a bit easier to merge. But also more prone to errors.