Yes, "texted" would be correct.
The second sentence is in the subjunctive, which uses the same form as the indicative. It is talking about things that the writer suggests would have happened if something else had happened. In this case, presumably they expected you to go inside instead of waiting for them outside, and they are saying they would have texted you if and when they arrived and did not see you outside.
But that did not happen - the writer is writing about what he suggests would have happened in other hypothetical circumstances, which is what the subjunctive forms indicate.