MTR 4 still have some issues / regressions introduced since MTR 3, which you can help the development of MTR 4 by contributing to such area.

• Train will not render with Sodium in MC 1.19.4 (Or Rubidium on MC Forge 1.20.1, switch to Embeddium in that case)
• F3+T/lagging when riding a train will kick the player with Invalid move player packet received (Can repo in Singleplayer)
• Dynamic Texture generation could potentially fail (java.lang.NullPointerException: Cannot invoke “java.awt.Font.deriveFont(int, float)” because “this.font” is null)
• Built-in R-train is lacking some interior decoration
• Sometimes certain train will be completely silent, then become normal again after riding the train for a period of time

• Exception/Crash when loading rail model which points to an non-existent file
• The resource pack creator cannot use non-alphanumeric characters such as CJK, and characters are garbled when exported.

• Train announcement still gets played even when in-game sound volume is 0
• Occlusion culling might be slow, causing trains & tracks to take a longer amount of time to show up (Resulting in train/tracks suddenly appearing out of nowhere, decreasing render distance helps)
• BVE sound would get stuck if the train got occlusion culled
• Rail model may occasionally flicker with a dimmed color.
• Some mod combinations would result in vehicles getting speed up with shaders enabled

• Ding Sounds in Elevator
• Scripting functionalities from Nemo Transit Expansion for MTR 3 (NTE)