It's fine if the tool has severe limitations at this stage. However, it's crucial to clearly state what those limitations are: not only does it prevent the flurry of complaints and chargebacks from customers who were disappointed that their specific case is unsupported, but it's also an opportunity to introduce a 'we're on this journey together' aspect that helps to make customers emotionally invested in the product.
Severe limitations? You sound like an a*hole tbf. The tool clearly provides the value, and it's a magnificent display how something like a simple LLM can be used to make your everyday life easier without compromising other minor stuff, you know, like letting other companies make profits by selling your own data?
Perhaps you live under a rock, I don't really know, but it maybe just happens that you're not a target audience? There's for sure many folks, and even more so companies, who will value their own privacy more over practice vs practise bikeshedding.
I have to go with GP here, being able to set the language to en_UK and en_US and getting the right corrections based on this setting is a minimal requirement for an English spellchecker. I can do without other English spelling variants but these two need to be supported correctly and consistently.