Anyone have any ideas?

DISCLAIMER: Almost all of the information I learned about below is a direct result of Azrael's hard work and testing with the player chat system. I take no credit for his discoveries and only offer the analysis we concluded from his findings.

Display text detection is not technically a global EUD: if you send a display text message to only one player, you can desync them by detecting that text and doing a global action off of it. In the same respect, player chat is not technically a global EUD: players can send and receive whispers or send to allies / a specific player in-game. Therefore, the player chat generation provided by this program isn't necessarily "safe" in this regard.

Furthermore, timing for messages sent and received by players is not synced to the game (unlike Display Text Message): messages are sent to the server, which then broadcasts it to the players as soon as it can. This has been measured (thanks to lil-Inferno and Origin for helping me and Azrael with measuring these numbers) to vary by as many as 5 hypertrigger cycles (and potentially more) to be received by all players. The reason this is an issue is because it means some triggers can fire on earlier trigger cycles for some players than for others, which would cause a desync on the end of that particular cycle. I currently do not know a remedy to this issue, and if you want to have chat detection as a mechanic in your multiplayer game, you'll have to regulate using a global timer when to execute chat actions (e.g., have a countdown timer and queue chat commands to run when the timer hits 0) and rely that your players won't attempt to send a chat command near the time that processing the actions occurs.

For this reason, player chat detection is significantly less effective than I had originally realized. Chat detection works pretty well has a noticeable chance of working without desynchronizing for a single chat command in maps that do not have hyper triggers, because the chances that the trigger will execute when not all players have received the message are decreased significantly. Raw chat detection on a map with hyper triggers will desync without fail.

TL;DR: Fuck text detection.

He made a map where he had a banning system and other stuff run by text EUDS.
They never failed or dropped anybody.

Roy, the download link for the hack detection is a link to a removed file.

Currently, EUPs aren't going to cut it for most HP modifying purposes. Though if your units health is <= 100 you can use set hitpoints just fine after detecting HP with EUD conditions, and if you're not picky about little differences it will work for units of almost any health.

Unit HP modifying. (Adding in particular)

If you mean healing, that's pretty straightforward to do using EUD conditions. Units only take damage between cycles, so you can just check the unit's HP at the beginning of each cycle, then set a DC based on that, then modify (add/subtract) from that DC, and then set the health percentage based on the DC at the end of the cycle.