Hello, I love that you have added independent emojis to the application, but they are in rasterized format. This causes them to be displayed correctly on all devices inequally. In addition the emojis used are incomplete, many of them have variants for hair and skin color. I leave several suggestions of open source emoji projects that have good support.
If you need help of any kind regarding this, count on me.
Emojis from Twitter (latest Unicode)
Emojis from Android (Unicode 10 Updated)
Emojis from OpenMoji (Unicode 12 Updated)