Hi,
You can check if the size of the used segment is larger than the spline section using the 'if' condition within the Arithmetic operator (return if(Input1 > XSectionLength, XSectionLength, Input1);). If it is, you can override its size to match it within the Transform Operator. Please find attached a sample scene (250317_XSectionLengthCheck_ITOOSOFT.max). I hope this helps.
Best regards,