40 months is in no way long. All my devices last well beyond 5 years. Then I repurpose them if they’ve incompatible with accompany services like the internet or something.

I’ve dealt with this exact issue. Increasing font size (increasing smallest feature size) helps. As does printing the letters first, as you have found. Although sometimes the letters dislodge and become floating letters a la Alice in wonderland. Depends on your bed adhesion.

Then linewidth on the perimeter touching the letter is something you could look into. (Reducing linewidth to reduce overlap/bleed)

It won’t be one magic solution, rather a combination of several factors all contributing to a more acceptable result.

I guess it’s possible to log the fact that a push notification was received and the time of it?