Coming at it from a completely different angle.
This is your first game. Voice acting adds hugely to the complexity.
First games are rarely that good, unless you are prepared to spend a very long time and restart it several times until you have the art and science of making a game reasonably well developed. It follows that to VA your first game might be a bad idea and a huge waste of your resources, including money. I strongly recommend that you make a much simpler game to start with, get to discover what the engine can do and how to do it and then think about making the game you currently have in mind.
However, as this is 'Games Mechanics Design' discussion cannot be about feedback only for a specific, individual game (Ideas and Prototypes is where that would go), so a couple of general points.
Games have a multi-national player base. To allow people who do not have English as their first (or maybe second or even third) language to play, written dialogue is also needed. Then you have the problem of people reading at vastly different speeds to the speed of the spoken word. Native English speakers will have finished before the voice acting and wait impatiently for the voice to catch up, or hit the action button and move on to the next bit, which cuts off the voice. Non-native English speakers will possibly be far behind. You also need written dialogue for those who are deaf or have only partial hearing, or who for various reasons do not play with the sound on, so it's not just a requirement for appealing to different nationalities.
Non-native English speakers could well struggle with the accents of the VA. Heck, I'm a native English speaker, and I struggle to understand some US or Australian accents (I'm a Brit), which again takes away from the whole point of having voice.
I have tried playing RM games with voice acting. To be honest, all of them were somewhere on the cringe-worthy scale, many of them at the top end. I have never finished such a game, just couldn't take it. As has already been noted, unless your VAs are top notch, it will come across as amateur, hammy, insert your insult of choice. RM games rarely sell enough to cover the cost of professional VAs, so you would need to have deep pockets and be prepared to make a loss.