I found info to use correct PayPal html variables and updated Confirm page code
<?php //WA eCart Validation
if ((WA_eCart_FormatNumber($eCart1->DisplayInfo("Price") - (($eCart1->DisplayInfo("Price")/$eCart1->TotalColumn("TotalPrice")) * $eCart1->GetDiscounts()), false, 2) > 0)) {
?>
<input type="hidden" name="amount_<?php echo $eCart1_Index+1; ?>" id="amount_<?php echo $eCart1_Index+1; ?>" value="<?php echo WA_eCart_FormatNumber($eCart1->DisplayInfo("Price") - (($eCart1->DisplayInfo("Price")/$eCart1->TotalColumn("TotalPrice")) * $eCart1->GetDiscounts()), false, 2) ?>" />
<input type="hidden" name="item_name_<?php echo $eCart1_Index+1; ?>" id="item_name_<?php echo $eCart1_Index+1; ?>" value="<?php echo $eCart1->DisplayInfo("Name") ?>" />
<input type="hidden" name="item_number_<?php echo $eCart1_Index+1; ?>" id="item_number_<?php echo $eCart1_Index+1; ?>" value="<?php echo $eCart1->DisplayInfo("ID") ?>" />
<input type="hidden" name="quantity_<?php echo $eCart1_Index+1; ?>" id="quantity_<?php echo $eCart1_Index+1; ?>" value="<?php echo $eCart1->DisplayInfo("Quantity") ?>" />
<input type="hidden" name="on0_<?php echo $eCart1_Index+1; ?>" id="on0_<?php echo $eCart1_Index+1; ?>" value="Embroidery Type:" />
<input type="hidden" name="os0_<?php echo $eCart1_Index+1; ?>" id="os0_<?php echo $eCart1_Index+1; ?>" value="<?php echo $eCart1->DisplayInfo("EmbroideryType"); ?>" />
<input type="hidden" name="on1_<?php echo $eCart1_Index+1; ?>" id="on1_<?php echo $eCart1_Index+1; ?>" value="Embroider Style:" />
<input type="hidden" name="os1_<?php echo $eCart1_Index+1; ?>" id="os1_<?php echo $eCart1_Index+1; ?>" value="<?php echo $eCart1->DisplayInfo("EmbroideryStyle"); ?>" />
<input type="hidden" name="on2_<?php echo $eCart1_Index+1; ?>" id="on2_<?php echo $eCart1_Index+1; ?>" value="Your Letters:" />
<input type="hidden" name="os2_<?php echo $eCart1_Index+1; ?>" id="os2_<?php echo $eCart1_Index+1; ?>" value="<?php echo $eCart1->DisplayInfo("EmbroideryText"); ?>" />
<input type="hidden" name="on3_<?php echo $eCart1_Index+1; ?>" id="on3_<?php echo $eCart1_Index+1; ?>" value="Special Request:" />
<input type="hidden" name="os3_<?php echo $eCart1_Index+1; ?>" id="os3_<?php echo $eCart1_Index+1; ?>" value="<?php echo $eCart1->DisplayInfo("SpecialRequest"); ?>" />
Now the options are being listed in the PayPal Sandbox Review Order details (options-bn.jpg attached) and are also listed in the PayPal email to both customer and seller. But still not on the checkout_success screen. Both the options and the item name are missing.
I updated the variable names in the checkout_success code to match those on the confirm page. I tried adding your code below in various places (after paypal php, before paypal php, before doctype) but just caused undefined variable error along with error messages about the undefined index items (checkout_success_1.jpg)