Well, technically nobody can stop you from calling it Farsi, but if you don’t call German “Deutsch”, or Spanish “Español”, or Russian “Russkiy”, or Arabic “Arabiyya”, I am wondering why you specifically chose Persian to refuse to use its name. I know it’s not just you though because other English speakers sometimes mistakenly refer to it as Farsi, and so it’s a trend that grew in the last few decades or so. I think it was probably the result of a disconnect where English speakers no longer knew what Persian was, and Persian speakers they met who also didn’t know English well enough to know it had a name in English already, would tell people the language is called Farsi.

Beyond just being a personal preference, there’s a few good reasons for not changing the name of the language. The often cited one is simply to not cause confusion, since the language’s name has been “Persian” in English for centuries, that it might make older references less clear. In my opinion, the better reason is that people sometimes squabble over whether to call their language Farsi, Dari, or Tajik, and sometimes that argument can by sidestepped by calling it Persian which is just a more inclusive name. Some Persian speakers even do this in their own language by referring to it as Parsi and not Farsi. Ironically, their argument is that “Farsi” itself is an exonym, but I don’t believe this is true.

I don’t think a language that’s a mix of Arabic, Hindi, Chinese, Indonesian, etc. ends up being any more of an effective competitor against any one of them than Esperanto already is. Esperanto may be primed to replace western European languages in particular, and Eastern Europeans also find it very familiar, but adding some Arabic although not enough Arabic would make it not only fail to easily replace English, but Arabic as well. Not that this is really the primary concern because any conlang could even be a priori and still be better than any natlang simply due to regularity. Regularity is the killer feature any conlang brings to the table. I just think Esperanto sweetens the deal by offering a quick transition.

So yeah I think you interpreted my comment as mostly correct, that the roots shouldn’t matter, but if they did I don’t see anything wrong or problematic with Latin roots. People usually come out against Esperanto as if this is something wrong about it, but Esperanto is the product of history and I don’t think its creators could have made a better choice really. Esperanto wanted to be humanity’s L2, and it ended up being founded on Latin, possibly the most influential language in human history, and close to the L2’s of most of the world, so even today the majority of Earth’s population, aside from their native language, have at least some familiarity with English, or Spanish, or French, or Russian… that lets Esperanto capitalize on something most people already know. It also capitalizes on what most people need to know, which is non-fiction (for example, scientific and academic articles) written in the aforementioned languages, which can be rapidly and effectively translated into Esperanto.