Some updates:
Conversation & Quest node links can now be deleted, just click the red button:
If there's only one remaining link to a node, a confirmation popup will be displayed. If the last link to a node is deleted, the node will still remain in the Nodes list but won't be accessible from the GUI.
(I'm not sure that I want to implement some clean-up logic here, maybe at some point expose a list of all nodes and let the user manually delete unplaced nodes from there?)
Regarding String Tables (including some stuff I've not documented yet because lazyness)
If a mod has StringTable entries with indexes that exceed the highest vanilla indexes, then the lowest of those indexes would be used as the "mod start index".
If the user tries to add a new entry and a start index hasn't been detected, a new value between 1'000'000 and 2'000'000'000 will be assigned instead. (Always ending with '000' to indicate in the stringtable files that it's the start index).
After that, the new StringTable entries will be added starting from that index.
High values and wide ranges are necessary to minimize the risk of mods generating overlapping keys, but won't look nice in the editor...
I've now made it so that if a start index is detected, entries exceeding that number will be shortened down to "k+x" in the gamedata editor, where x is the offset from the start index.
An example from Spoils of Caed Nua: