Is this little text I've written written correctly?

Salvete!

I’m at Familia Romana’s 9th chapter, which explains the genetive plural of the third declension. I thought it would be a good idea to explain it in Latin. Here it goes:

Si numerus syllabarum nominativi singularis et numeris syllabarum genetivi singularis sunt æqui, genetivus pluralis -ium finitur.
Si numerus syllabarum nominativi singularis et numeris syllabarum genetivi singularis non sunt æqui, sed ante terminationem sunt duæ consonantes, genetivus pluralis quoque -ium finitur.
Si numerus syllabarum nominativi singularis et numerus syllabarum genetivus singularis non æqui sunt, neque ante terminationem sunt duæ consonantes, sed una tantum, genetivus pluraris -um finitur.

Is this correctly written? As you can see, I repeated “numerus syllabarum” a lot: I was not sure how to avoid this repetition. Besides any concord or syntax errors, if you can point me anything that would improve my style, please point it too! (E.g. if I used an uncommon word for which there is a more common equivalent, please point me this equivalent.)

-John

No John I’m afraid that won’t do. You could try
Si nom.sing. tot syllabas habet quot gen.sing.,
(or Si nom.sing. eundem habet numerum syllabarum quem gen.sing.,)
tum gen.plur. syllabis -ium clauditur.
Etc.

But if you really want to know how to do this sort of thing you could take a look at Keil’s Grammatici Latini (available in the Internet Archive). Good luck!

Much thanks for the correction and for the recommendation!