Are you asking if there’s any way to create new ships / modules / etc with their own attributes / effects? Unfortunately there isn’t a user-friendly way of doing this. pyfa is open-source, so you can always open up the eve database that pyfa ships with and modify to your hearts content, but you will also need to have intrinsic knowledge of the data and how it works, as well as python (the effects that describe how items modify stats are written in python).
pyfa does have limited support for changing stats through it’s Attribute Editor - you’re able to load up ships / modules / etc and edit it’s base attribute. For example, if CCP is thinking about increasing the power usage of a Web II, you can search Web II and change the
power attribute value. However, this doesn’t support 1) creating new items (only editing existing items), or 2) adding / editing effects (so, if there is a new ship out that has a specific combination of effects, you’re gonna have to hack at the database in order to support it).
There has been talk in the past about adding such a feature, but it’s been on the backburner. There would be a lot that goes into building the feature out and making sure it’s decently user-friendly. Maybe sometime in the future!