While using the Wireless Crafting Terminal (its interface is open), and not having clicked in the search/text field, if I hit shift+9 (for an opening parenthesis), the server crashes, and my Wireless Crafting Terminal has been deleted from my inventory once I get back into the game.

If I click in the search/text field, there is no issue. I can type "(legacy" without crashing the server.

Wireless Crafting Terminal version: 1.12.2-3.9.64
Modern Skyblock 3 version: 3.4.1.2

do you have access to a crash log? if so, can you pls go to a site like pastebin and paste it, then post that url?

I looked at that because it seems wiered ... It also works with Shift + 8 in the 8th Hotbar Slot. What happens is that the WCT gets shifted into the Crafting field and then the Server crashes.
I also have a Crash log for that problem:
https://hastebin.com/iyigeduwuw.coffeescript

I hope I can help you with that.

Update: Also works in Single Player and also with the 6th and 7th Hotbar Slot, at least for me. Additionally, your Mouse must be over the Crafting Grid inside the Terminal. I also found a other Bug with the Offhand, in where the Terminal won't open if you right-click it. If you then open it via the Keybind and take it out of the offhand slot, the Gui closes and the Terminal goes invivible, until you open and close the inventory, then it will drop on the floor.

just replicated in RV5 and RV6 live on stream and fixed it :D thanks for the reports! just doing a RV6 test to ensure the fix works there as well, then I'll push fixes