[Baertram]

As sirinsidiator and Sharlikran (in detail) and me already told you you should NOT go on trying as there is no way
(SV are stored in the game memory. Altering it outside the game won't change the memory. Only reloadui does and it will overwrite from ingame memory first, so you're idea won't work and was answered already in several other threads too -> I'll add that to the "what addons cannot do" so one finde it more easily.),
and if any way works out it's not intended to work!


ZOs will shut it down, most likely affecting other API which might (did in the past) break other addons. So please do not start this and make all the other community members here suffer from it in the end just because you think it could be doable and would be legit.

If your really want to know if it's legit ask ZOs!
If they allow it to you, I'd say they should not revert later on. But you should clearly describe them what your idea is, technically.

Thank you for your understanding that not all nice ideas will be doable, or at least not for long, and having downsides for all others in the end.


Edit:

About TTC:
That's why addons like TTC write data to new lua files (no SV!) before the game client starts as afterwards it's not possible anymore. The client of TTC downloads the data and updates a price*lua file in the addon folder (no sv file) for offline usage. It's just loading this file, which needs to exist before the game client starts!

The client, while running next to the game and if enabeld in the ingame addon settings to collect guid listings and upload them to the TTC website, does the following: The addon ingame collects guild listings and writes it to the internal memory. On reloadui it writes data to the SV file.
The client checks for a timestamp change of the SV file, or similar, and uploads the listings to the TTC website.
So this is never a realtime exchange of data. And it is, like Sharlikran wrote above, a gray area and ZOs never allowed (nor totally disallowed) it!