
Samsung Galaxy Style DUOS
The latest firmware for Samsung Galaxy Style DUOS (SCH-I829) is I829KEANH3 with Jelly(Android Bean), released on September 24, 2014 for 1 region (CSC). Every official firmware build for SCH-I829, newest first: one row per build with all regions (CSC) that received it.
Each firmware build has its own page at https://samfirm.shop/build/{PDA}, where {PDA} is the build number from the list above. Example: https://samfirm.shop/build/I829KEANH3
The newest build, I829KEANH3, was released on September 24, 2014. No new build has appeared for 147 months, so regular updates for this model have most likely ended.

SCH-R970X

SCH-L710

SCH-I939D

SCH-I545PP

SCH-I545L

SCH-I435

SCH-I545

SCH-P709
The latest build for SCH-I829, I829KEANH3, was released on September 24, 2014 (12 years ago).
SCH-I829 has had no new firmware for 147 months, so regular updates have most likely ended.
Yes, all firmware files for SCH-I829 are 100% official, original, and obtained directly from Samsung servers.
To flash SCH-I829, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing SCH-I829.