Unfortunately the text format provided by Watchout doesn't seem to be following any open standard. It would be great if it was JSON, is there by chance an option to get the data as JSON?

So there isn't anyway to copy the text to a system clip board with JavaScript in Isadora. The JavaScript actor is very fast using the V8 engine, but it is sandboxed, it can't connect outside of Isadora, and doesn't support any browser specific JavaScript functions, only the core JS specification.

If you can explain exactly what you are trying to accomplish. step by step, as far as data flow, I will think through your possible solutions.

Once I have that figured out, I want to add variables to change the keyframes from the actor input rather than editing the text directly each time I need to add a new fade time. I'll end up adapting this to all of the keyframe/tween types in Watchout.

Feel free to just point me in the right direction! I haven't written Javascript from scratch; I always edit things I find online, but would love to change that.

UTF8 DATATON_DFC_DATA_590925_620721_AUC069 {
    "Structure and File Format (C) Copyright Dataton AB" 2022 1
    "WATCHMAKER" 6 7 2 0
    ObjTransferable ObjTransferable struct extends {
        TextTransferable struct extends {
            Transferable struct {
            }
        } {
        }
    } {
        mObjData list object true,
        mClassName string
    } {
        { // mObjData
            TweenPointTrack struct extends {
                TweenTrack struct extends {
                    TweenParam struct {
                    }
                } {
                    mExpanded bool,
                    mHeight int
                }
            } {
                mPoints list TweenPoint struct extends {
                    TweenParam
                } {
                    mTimePos float
                } true,
                mExpr reference TweenExpression struct {
                    mExpr Expression struct {
                        mItems list ExprItem struct {
                        } true
                    },
                    mExprY Expression,
                    mExprZ Expression
                } false
            } {
                true, // mExpanded
                0, // mHeight
                { // mPoints
                    OpacityTweenPoint struct extends {
                        _tween1DValue struct extends {
                            _quadTweenPoint struct extends {
                                TweenPoint
                            } {
                                mSmooth bool
                            }
                        } {
                            mValue float
                        }
                    } {
                    } { 0, false, 0 // mTimePos mSmooth mValue
                    },
                    OpacityTweenPoint { 5, false, 1 } // mTimePos mSmooth mValue
                },
                #0 // mExpr
            }
        },
        "TweenParam" // mClassName
    }
}

assuming the format of the String you receive always has the same number of segments (delimited by spaces), the following Javascript should work nicely for you.
It takes the string, splits it into an array of segments based on the space delimiter, then parses the selected segment into base 10 integer.

// iz_input 1 "target [0 based]"
// iz_input 2 "watchout reply"
// iz_output 1 "targetSegment"
function main()
{
    var target = arguments[0];
    var segments = arguments[1].split(' ');
    var targetSegment = parseInt(segments[target], 10);
    return targetSegment;
}

You should be able to paste this into a Javascript actor and feed your text to the second input.
The first input needs to be an INT that targets the correct segment (7 is what works for me with your test string).
NOTE: The Javascript actor has mutable input and outputs, so be sure to mutate them to the correct types. ( like to use Trigger Text, and Trigger Value actors to ensure they are locked to the right types before I connect other actors)