Automatic dosing issues
The EU had these systems for decades now.
Some systems have more issues, some less.
The biggest issue is not necessarily type of detergent/softener, but time.
If you leave for weeks, manufacturers recommended emptying tanks.
Most machines have flushing cycles for the lines in case of either changing detergent or leaving the system unused for long periods of time.
Given that within the pipe, there is no contact to air, the time until issues arise isn't terribly short.
But it can happen, and that usually means taking apart the system and flushing out all the piping or changing it out.
Some systems have the pumps right on the drawer which means there is less distance between where the detergent exits and the reservoir, others like Mieles TwinDos have quite long pipes.
In general, under normal use of the system (once a week) and with minimal care, you shouldn't run into issues.
On the topic of oversudsing with automatic dosing: These systems usually need to be told a specific amount for a specific load.
Since US detergent manufacturers appear to be less keen on providing such information, most manufacturers just "guestimate" what to dose.
Thus, he might have just misadjusted the system.
Some suds are usually not a big issue, but as soon as a closed suds layer with a sufficient thickness (half an inch or more) forms it certainly is to much detergent.
That is as long as rinsing performance is still up to par.
Some detergents just suds more even with correct dosing yet still rinse away nicely.