Excel conditional formula

A TypeScript option for the exercise only (my 3rd script - be gentle please)
NB: Do not use it with large ranges

// TypeScript: Color cells on condition:
//  IF cell value in Range_to_color + Increment = any cell value in Range_of_references
//  THEN color cell in Range_to_color
//
//  ASSUMPTION: Range_of_references & Range_to_color consist of numbers only (empty cells OK)
function main(
  workbook: ExcelScript.Workbook,
  Range_of_references: string = "A2:F2",
  Range_to_color: string = "A3:F3",
  Increment: number = 5
) {

  function normalizeAddress(address: string): string {
    // Trim and convert to uppercase for consistent address validation
    return address.trim().toUpperCase();
  }

  function isValidAddress(address: string): boolean {
    // Basic regex to validate Excel-style range references (e.g., A1:B3, B10:C10...)
    const regExcelRange: RegExp = /^[A-Z]+[1-9][0-9]*:[A-Z]+[1-9][0-9]*$/;
    return regExcelRange.test(normalizeAddress(address));
  }

  // Validate the input address format (e.g., "A1", "B100", "AZ35")
  if (!isValidAddress(Range_of_references) || !isValidAddress(Range_to_color)) {
    // Execution stops on throw (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/throw)
    throw new Error("Please enter valid range address(es) like A1:D1, C4:G4, ...");
  }

  // Get active worksheet and ranges
  const worksheet = workbook.getActiveWorksheet();
  const sourceRange = worksheet.getRange(Range_of_references);
  const targetRange = worksheet.getRange(Range_to_color);

  // Count columns in targetRange
  const targetColumns: number = targetRange.getColumnCount();

  // Flatten sourceRange (workaround to .flat() that raises a warning in Excel TS console)
  const flattenedSource = sourceRange.getValues()
    .reduce((acc, row) => acc.concat(row), []);

  // Iterate cells in targetRange
  for (let i = 0; i <= targetColumns; i++) {
    const currentCell = targetRange.getCell(0, i);
    // Invoking read methods inside of a loop could lead to slow perf.:
    const currentValue = Number(currentCell.getValue());

    // Iterate flattenedSource
    for (let j = 0; j <= targetColumns; j++) {
      // If currentValue (in targetRange) + Increment = current flattenedSource value...
      if (flattenedSource[j] === currentValue + Increment) {
        // Color the cell in targetRange
        currentCell.getFormat().getFill().setColor("#C1F0C8");
        break
      }
    }
  }
}