Sorry for the late reply, until now i saw your reply. Heres the ROM (i dont know how to make a patch, so im sending the full ROM)
This one is the one that has the Custom Tech
// Extras
Extra: There is also a problem where i have to manually change in Hi-Tech the "moving towards target part" every time i want to play it (It changes for some reason I dont know).
Extra 2: I know this may have been done by someone else already but i have a ROM with Crono's and Lucca's techs/elements swapped (tweaked a couple of animations + "Luccanaire" softlocks the game, other than that it works fine. im assuming that maybe its some coding in the tech itself).
Extra 3: About the Dual/Triple Techs, havent tried to modify one yet, i just know that whenever i want to modify for example, Fire Sword 2 (Crono + Lucca), a minimal change to the tech, breaks it and makes a softlock whenever it is used, even when changing it back to its Vanilla values (you can check that for yourself by modifying a dual tech, just change for example, an animation).
Back to the main topic, in the attached file its the ROM with the tech, about the other problems im assuming that its because of
1. SNES limitations/Code limitations
2. Maybe some techs have "Custom" coding that break the tech when a minimal change is made
3. it could be a problem with Hi-Tech itself
Download as the attached file didnt work (Only modified tech is "Slash", which i called Thunderblade, the name isnt changed in game):
https://drive.google.com/file/d/1LuJK7hWZg-Wyvjxf1YBHzQE5qcqpqn-B/view?usp=sharing