Hi,
If you don't set any price in the variant, you can use the "main product price percentage" input to provide a percentage value. If you do so, the system will calculate the price of the variant as a percentage of the main product price. So if you have a main product with a price of 60€ and the variant has a main product price percentage of 50%, the price of the variant will be 30€.
Regarding the "text", I suppose you're talking about the variant description HTML editor ? There seem to be an issue between the HTML editor and the form customization mechanism in some cases. But we were not able to identify the problem as there is no error displayed or in the JS console when that happens. In HikaShop 4.7.0, we've added a button on the main product edit form to turn off the form customization, which will prevent the issue, but you'll loose the form customization. Another solution is to use the "none" HTML editor in the Advanced tab of the HikaShop configuration so it will be just a normal text area. If you're familiar with HTML, it can be a solution.