Hi @Daniel_Weikert , I don’t think there is a list but in general the nodes that use are based on actual programming language need to add the extra backslash.
e.g. Requiring double-backslash:
String Manipulation, Column Expressions, Java Snippet
Not requiring double-backslash:
Rule Engine
Row Based Rule Filter
Regex Split
Column Rename (Regex)
For the “scripting” nodes, there is a small visual clue as the colour of the string changes. If the String is not displayed as red when you enter a backslash, you need to enter a second one! This is because the script editor cannot determine that the string is being “closed” correctly, or something like that…
e.g.
String Manipulation:
Column Expressions:
Rule Engine (doesn’t use double-backslash):
Even the java snippet node does have this visual clue, although it’s not quite as obvious because the colour changes from blue to black. Although it will also underline the line, and when you move off it will highlight it.
I think there might be some cases though where you need to enter a third backslash. It depends on how many “levels” of interpretation there are before it actually gets to run the resultant code, but maybe that’s a story for another day… or when I can find an example… 
The main thing I think is to be aware that double-backslash may be a possibility so if you hit problems you have an idea where to look. 