Understanding Blender studio's SmokeFX for <Charge>. i dont get it. help

Hi! Can I post a question on this board that I got while working on a project?

Currently i’m trying to recreate Blender Studio’s FireFx [https://studio.blender.org/films/charge/3b0f29b4825fa2/?asset=6132]
and i have a question thier Sprite sheet UV.
How to get it work well on the sheet that have diffent value of Columns and Rows like 3x4 sheet?

this is my simple recreate version.
[https://drive.google.com/file/d/1vCKRi4-mupfy94JlgdEgUWgfKVG_82wk/view?usp=drivesdk]
(i cant… upload file… becuz im noob… ;_; )

i didnt understand nodetree completley
so i just think ‘oh Wrap node’s max value is 49.999. 7x7(there original sheet) is 49, so… i just change that value to 3x4+0.999.’ ‘and why did they added floor node? why not just wrap 49 at the first time?’
ofcourse node didnt work well. the number dont go in order and also skip some number.

so i just tested with 3x3 sheet. and changed Wrap node’s max value to 9.999
and than it goes work weck too. the number go in order but it just repeat 7 two times. weird. so i just changed Wrap node’s max value to 9.5, it works well. why???
any help for me? i really want to understand this math function for FX study ;(

Maybe have a look here?
Product Search - Blender Market

Sprites aren’t really the way to go imho.