Excel Challenge - Pivoting poorly structured data

This is from an ExcelBI challenge.  I thought it may be worth while posting my solution here as a demonstration of modern Excel methods.

Challenge

Like many of such challenges, the natural solution approach is to use BYROW but that creates the usual 'array of arrays' error.

Solution:

Gradually I am moving to a point at which I have no formulas showing in the workbook other than calls to Lambda functions.  In this case, the worksheet formuloa is

= PIVOTBYCATEGORYλ(OrderTbl)

The function works row by row apportioning the amounts against the listed categories 

PIVOTBYCATEGORYλ 
//  Groups and pivots table by category
= LAMBDA(table,
    LET(
        normalised, BYROWλ(table, APPORTIONλ),
    //  Identify fields from normalised table
        dimension,  TAKE(DROP(normalised,,1),,2),
        category,   TAKE(normalised,,1),
        partCost,   TAKE(normalised,,-1),
    //  Pivot by category
        return,     PIVOTBY(dimension, category, partCost, SUM,,0,,0),
        return
    )
);

The function APPORTIONλ divides the amount between categories so each record within the source data returns a number of rows

APPORTIONλ
// Splits by category and assigns costs
= LAMBDA(record,
    LET(
        category,   TOCOL(REGEXEXTRACT(INDEX(record,4),"\w+",1)),
        amount,     INDEX(record,3) / COUNTA(category),
        year,       YEAR(INDEX(record,1)),
        region,     IF(LEN(INDEX(record, 2)), INDEX(record, 2), "Unknown"),
        broadcast,  B∕CASTλ(HSTACK(region, year, amount), category),
        return,     HSTACK(category, broadcast),
        return
    )
);

/* FUNCTION NAME:  B∕CASTλ
     DESCRIPTION:  Broadcasts the terms of a vector over the shape of a second array */
B∕CASTλ = LAMBDA(vector, array, IF({1}, vector, array));

The key to making the formula work is the function BYROWλ that I wrote to generalise the inbuilt but over-restrictive BYROW function.

The PIVOTBY function returned the required crosstab from the  normalised data array