The most interesting part is the comment saying the company is having trouble hiring engineers so they went offshore. There is not a shortage of talent, there is a shortage of talent at the discount price point the company wants to pay. Not saying that to bad mouth the company, but understanding that helps you to understand why you are getting what you are getting in India too, it is the same there.
I have managed people in India off and on since 1999, and for the past 3+ years have been working at a startup where we have an entire division in India, including engineering. So I have to deal with recruiting, hiring and managing in India for engineers, I travel there reasonably often. One of the key things to know, really good India engineers are being paid $35-50 USD per hour, not $10-$18. Yes, you can find people for less money that are awesome, but as a foreign company that isn't on the ground in India that won't happen. You will get consulting companies that provide you people they are hiring for 8-12 lakhs INR (~$12k-$17k USD/year) and charging you what seems like a good deal at $15/hr but this isn't a deal because you will be answering questions like you are for the next eternity. Good consulting companies that employ more experienced engineers are typically charging more on the lines of $50 USD/hour, you still aren't getting the top 20% but you at least aren't getting the bottom 20 either.
To be very clear, there are extremely talented engineers in India, it isn't a capability issue, but it is a numbers and recruitment issue. When I say it is a numbers issue, India educates more engineers than the U.S. by far, and so it is far more likely you are dipping into the 80% side of the pool not the top 20%. Engineers that are talented in India make very good money, in fact very comparable to many European countries anymore. I know friends there right now that are charging ~$50 USD/hr and they are a steal, here in the U.S. they would easily be worth double in a consulting engagement.
So I only mention all that because essentially you likely have very junior engineers that are just not familiar with either the framework in total or just don't have the experience. And this can be hard to tell from their CV and an interview because it may look great (if you even saw one). Also, when I recruit in India it isn't uncommon for people with 3 years of experience thinking they are senior and deserve more money but they are incapable of doing basic tasks unaided, and so you wind up filtering through a lot of these to find the good ones. Again, a bit of a numbers game.
As for what you can do. One of the things I love about the Indian culture is they aren't offended by direct (but respectful) comments, and in fact they prefer it as they feel you respect them more when you are direct (just understand they will do the same generally). Of course it should go without saying, but you should never be disrespectful of course. Being direct in your feedback on what they need to do is also what makes them feel better in their job as well, so their performance gets better. The key thing is don't make this an adversarial situation, that will not benefit you or the team. Instead, ask them to send you questions on Slack or whatever but give them guidelines, and direct them to some resources where they can learn around some of the common coding issues your team is dealing with or you see them having. This will be warmly received, and appreciated. It will also start to cut down on the number of questions because after 2-3 times you should refer them back to the reference material, and document that you have done so.
My contact is in my email, happy to help you (give you ideas/tips) offline if you'd like. And don't feel bad about the communication, I literally have over 20 years off and on of working with India based people and I still sometimes struggle. I just tell them, hey I don't understand, can you slack me what you just said or a lot of times one of the other Indian peeps will clarify for me. No different than I have had that talking to people with a Boston accent, or a deep south drawl and I am like WTF did you just say? I think of it the exact same, no different IMO.