Hi Anna Catarina,
Thanks for updating Cairo LRT. I was initially considering tagging the infrastructure as railway=light_rail, too, but decided against it. Because different than the name suggests more elements of the infrastructure actually are S-Bahn like train infrastructure. Primarily the station infrastructure, top speed and train capacity speak against light rail categorization. See also the first paragraph in the wikipedia article: https://en.wikipedia.org/wiki/Cairo_Light_Rail_Transit and the comment from an established urban rail expert on https://www.urbanrail.net/af/cairo/cairo.htm
I would suggest to keep the tagging as railway=train therefor. Let me know if you are okay with reverting the tagging