HikaShop is a great eCommerce product for USA businesses, it just seems that you have some particular issues that require a paid developer to help you finish your site. You need someone who can help you with properly configuring TaxCloud itself, verify all of the HikaShop settings, customize your emails, etc. to provide the specific result you need. It really goes beyond software support to ask the HikaShop team to solve all of that for you.
If you are frustrated with TaxCloud but still want automated tax calculation for HikaShop, you could also consider AvaTax. We have built an AvaTax globally certified plugin for HikaShop, including partial and paid return handling. The plugin is free, but you do need to pay a fee to Avalara to use AvaTax each month. So if you want to stay with a free solution, then your two choices for tax calculation in HikaShop are to use the built in tax system or TaxCloud.
I know taxes are vitally important to get right before you launch your site, so it's frustrating if it takes a while to get everything working smoothly. Hiring an expert to help you get past this point will alleviate that frustration and let you focus on your business instead of trying to master the intricacies of configuring taxes.