The update makes the game playable in handheld mode. However, it does not fix the core gameplay (the confusing map layouts) or add new chapters. This is strictly a stability patch.
Improper installation of NSP updates—specifically if the update version mismatches the base game version or if the installation is interrupted—can corrupt the Switch's NAND (internal storage). This often results in a boot loop requiring advanced hardware-level repairs. Garten of Banban Switch NSP UPDATE
If you are using a (dumped from your own legitimate cart) on an EmuNAND (offline partition) with proper blocking of Nintendo servers, the risk is extremely low. However, installing any non-official NSP on your SysNAND (Stock OS) will almost certainly result in a ban. The update makes the game playable in handheld mode