I have an idea — and it's surely insane — that could put an end to this shortcoming.
The lerfu pro-sumti could be repurposed. In a big way.
Instead of having them refer to a previous word that begin with the corresponding letter, each lerfu would have a defined meaning, a type of thing that it refers to, reliably. There would be one that refers back to the most recent living thing, the most recent person, object, abstract thing and many more. Below is a list of possible referents. I based the letters on gismu to make them easier to remember:
jmive (gi'e na remna)
dacti (gi'e na jmive)
abstract, immaterial, thoughts, ideas
Let us look at some of the amazing things we can do with this.
(1) na go'i .i mi pu no roi zvati sy
"No. I have never been there."
(2) fy dunda lo kargu junla ny
"She gave him an expensive watch."
(3) mi .e lo mensi be mi pu klama sy .i ku'i fy na nelci sy
"Me and my sister went there, but she didn't like it."
(4) ko xrugau dy lo pu te tolcri be fi do
"Put it back where you found it."
(5) my cinri sidbo
"That is an interesting idea."
I can think of more things to put in the above table, this is just a proof of concept, for you to try out.
Though let me warn you. If you use this for a while, you might never want to go back. It's so powerful! It almost feels like cheating, that's how good it is. Suddenly, all the prior clumsy make-shift anaphora mechanisms are no longer needed, and what used to be a difficult area of the language has turned into a cakewalk.
But of course this whole idea is crazy.