Need help with replacing Trane Tracer system with ???

I do not have much experience with Trane light commercial package units and I find it hard to
get any information.

Here's what I'm dealing with.
There is a building with Trane rooftop package equipment providing the hvac.
There are nine package units consisting of 7.5 and 10 ton units.
All nine systems are controlled by a Trane Tracer system.
The customer recalls someone accessing the Tracer system a long time ago but nobody has
a clue how it works anymore. At one point an hvac contractor replaced some thermostats
with Honeywell stats and wired some of the dampers open and who knows what else.

The Trane Tracer system is still functioning but cannot be accessed because nobody remembers the password.

The customer would like to be able access the hvac system in order to make adjustments
, check temps. etc.

My boss says, "Forget that Trane system", "Trane won't help you figure it out, they will want to do all the work and will charge a fortune".
After seeing what happened to the current Tracer system, I can understand why Trane doesn't want other people working on their systems.

I feel that we should restore the original Tracer system and or do an upgrade using newer
Trane controls.

My boss wants to rip it all out and put in Honeywell Redlink controls.

What do you think?

I would appreciate any ideas or help.