I was able to edit the systems.cfg file to help it autoland. Under the [AUTOPILOT] section, just add these or change them from 0 to 1.
autoland_available = 1 ;
pitch_glideslope_arm = 1

1. Fix the Engine Logic (engines.cfg)
Legacy FSX conversions usually fail because MSFS expects modern turbine parameters.

Open engines.cfg (or aircraft.cfg if it's an older legacy layout).

Look for [TurbineEngineData] and [JetEngine] sections.

Force MSFS engine parameters: Ensure engine_type = 1 (Jet).

Fix the throttle response: Check the thrust_scalar. If it's broken, set thrust_scalar = 1.0.

Fix Afterburner: Add or update these lines under [JetEngine]:

Ini, TOML
afterburner_available = 1
afterburner_throttle_threshold = 0.90
2. Swap the Flight Model (flight_model.cfg)
If the throttle is stuck at 10%, the sim's modern physics engine is clashing with legacy tables.

In flight_model.cfg, look for [FLIGHT_TUNING].

Add or change this line to force the legacy parameters to translate properly:

Ini, TOML
modern_fm_compatibility = 1
Alternatively, under [HEADER], ensure the format version matches MSFS standards (game_version = 1.18.0 or higher).

3. The Catch (The Switches & Gauges)
Editing the .cfg files will not fix the dead cockpit buttons.

Those switches rely on code (.xml, .wasm, or legacy .dll files). Config files only control background math (weight, thrust, drag, fuel). To get switches working, someone would have to rewrite the entire panel.cfg and code HTML/JS or WASM gauge overlays from scratch.

The Practical Solution
drop in the engines.cfg and flight_model.cfg from a working default MSFS jet (like the darkstar or a default airliner) as a temporary template, or use Slew Mode (Y key) to get it airborne. But at the end of the day, it's putting lipstick on a pig.

This FSX Model Plane I Cant Work Animated Cockpit And Effect Also Not Support MDL Model