I'm going to be brutally honest... there's not much game to play here. The game literally tells you what to find and where to find it when you touch that teleport spot.
If you want the player to find all spots before they move on to the next room then I suggest having the teleport spot appear only once all hints have been found. (maybe create a "hint count" variable and add 1 everytime the player finds a hint then set the teleport to appear only once that variable has reached the required number then once the player has moved to the next room, set the variable back to 0 and repeat).
Also I feel the character being able to go through walls and furniture is a heavy flaw as you need to be in a very specific position to investigate a spot which can get very annoying. Maybe instead of going through furniture, you could lower the opacity on the character to show they are a ghost (I assume this is why you made it that way).
Finally, I think this game would benefit from a lot more interactions. Not necessarily with the characters, but as an investigation game, there should probably be at least a little bit of dead ends (investigation wise) and red herrings and lots more to examine.
And also, most importantly, don't spoon feed the answer to the player. Let them come to a conclusion themselves. The goal of a mistery game is to solve the mistery. What's the point of playing the game, if the game plays itself is what I'm saying.
Not a real critic but if you decide to attempt to create your own maps ands sprites, it could definitely spruce up your game and add to the value but I also get that not everybody has the will/skills to make that or money to have it commissioned
Honestly, the game summary sounds amazing! So I'm a bit disappointed that the game itself didn't meet the set expectations. If you ever decide to improve upon Silent Banquet, I'd love to replay the game and see if it rose to the challenge
Keep developping and have a great day!