A number of Chinese cross-border exporters expect the Trump administration’s erratic trade policy to continue testing their stamina and resilience, days after the tariff truce between Beijing and Washington was extended for another 90 days.Those concerns were raised on the sidelines at Friday’s opening of the semi-annual China Cross-Border E-Commerce Trade Fair in Guangzhou, capital of southern Guangdong province, which concludes on Sunday.With booths at the fair, major online retail platforms...