Before starting, it seems a little out of place to make a tool for “something old”, which is no longer in the latest version of Renoise…
There are two ways to automate, directly in the pattern editor in the effects column or in the automation editor.
This seems to be the old RingMod. If you want to build a tool, it may involve using the old API, of the Renoise version with that RingMod. The current RingMod is different, supposedly with a different API.
That said, I suppose you want to vary the frequency of the oscillator along the sequence of a pattern. This implies knowing the number of lines of the pattern, since the resolution will be a variation of the value for each line. If you have 64 lines, you can only vary this value 64 times if you use the effect column of the pattern editor. Instead, you can handle more variations if you use the automation editor (many more points).
Then, there must be a relationship between the number of lines in the pattern (its length) and the groups of values in your Excel file. That is, you need to know exactly what you want to do.
Some notions. The Renoise API can extract data from XML files, but these documents must have a specific structure. LUA can extract data from entire lines within TXT text files. That is, you can create data banks, each line could be a table. In this way, it is possible to import the entire line (the table) through LUA to handle it by physical memory. To change banks, you just have to modify the route. The API allows you to change the path of a file. This would be the example of a TXT:
They are 3 lines, then you get 3 tables.
As a previous step, with the API you can load a specific DSP effect chain (the RingMod) in the selected track. Then load any point of this TXT (or XML) by previously importing it into memory (it would be equivalent to defining a temporary equality). Each point would be a value in Hz, and the conversion is very simple. You just have to meet the minimum and maximum limits (the valid range). All this could be done with a single shooting function.
In addition, it is possible to create a nice GUI where the values appear visually before entering them in the automation editor, or in the pattern editor in the effect column.
But going back to the beginning, you should know exactly what you want to achieve, and this would make more sense if the RingMod were the current one, not an old version.
This is the new version: