The Aixt to V transpiler performs general equivalences between both languages, but the specific characteristics of each microcontroller or C compilers, such as types or necessary header files, must be recorded in a setup file in .toml format. The main idea of using that setup file (port_name.toml) is to facilitate contributions (appending a new device or board) by simplifying the knowledge required on the part of the contributor. Each contributor has to code the API functions for the specific C compiler and also the setup file.
Anyways, you can contribute in any other part of the Aixt project, all your contributions will be well received.