Coffee spilled on 2018 Touch Bar MBP. Still working with some problems. What to do?

"Recently"… unless it was in the last 5 minutes, you likely missed your chance.
The absolute first thing to do is stop using it, disconnect the power, including the battery, strip it down & start to dry up as much as possible.

Don't hope it will be OK.
Don't put it in rice & expect it will just get better.
Don't plug it back in to see if it still works.

Your two main enemies are short-circuit & corrosion.

Any liquid containing a high percentage of water will immediately short-circuit anything it touches, potentially causing component damage or even fire.

Any non-pure liquid will then start to corrode the delicate circuitry, quite rapidly in the presence of electricity.

The faster you can get the power removed & the circuits cleaned using isopropyl alcohol, the better the chance your machine will survive.

For additional reading -
No sound (speakers/jack) + microphone's dead after spilling water
&
What procedure should be followed post spilling fluids onto a MacBook keyboard?