BrandsRandomSetProp

CModule::IncludeModule("highloadblock");

$IB_ID = 89;//IBLOCK_ID
$HL_ID = 38;//HLBlock_ID
$count = 10;//Count of HL block items
$PROP_CODE = "MANUFACTURER"; //PropCode

CModule::IncludeModule('iblock');
use Bitrix\Highloadblock as HL;
use Bitrix\Main\Entity;

$hlblock = HL\HighloadBlockTable::getById($HL_ID)->fetch();
$entity = HL\HighloadBlockTable::compileEntity($hlblock);
$entity_data_class = $entity->getDataClass();
$entity_table_name = $hlblock['TABLE_NAME'];

$arFilter = array(); //задаете фильтр по вашим полям

$sTableID = 'tbl_'.$entity_table_name;
$rsData = $entity_data_class::getList(array(
"select" => array('UF_NAME'), //выбираем все поля
"filter" => $arFilter,
"order" => array("UF_SORT"=>"ASC") // сортировка по полю UF_SORT, будет работать только, если вы завели такое поле в hl'блоке
));
$rsData = new CDBResult($rsData, $sTableID);
$arBrands = array();
while($arRes = $rsData->Fetch()){
$arBrands[] = $arRes['UF_NAME'];
}

$res = CIBlockElement::GetList(Array(), Array("IBLOCK_ID"=>$IB_ID));
$i = 0;
while($ob = $res->GetNext())
{
    CIBlockElement::SetPropertyValues($ob['ID'], 47, $arBrands[rand(0, $count-1)], $PROP_CODE);
$i++;
}
echo $i;