t's quite possible. We may roll bad or they may roll good, or both. But in that case we'll still have chances... If they'll, jump that will disrupt their attack anywayThat we'll get lucky with the spear, that Gwen get lucky with her rolls, that unicorns get unlucky with their attack rolls. But failed jumping attempt may not leave us such chances, because we'll become a siting duck
If we get wounded here, it's basically game over. Any wound will make something that's already very difficult even harder for us. This is the *hardest* fight we've ever been in, and it will come down to using our worst skills at higher penalties than usual, if we get hurt by charging unicorns and/or they dispatch Gwen our chances of success go from not very good to absolutely awful. If we fight we *need* Gwen to roll good, we *need* to roll good and then we need to hope that all of the unicorns roll worse than we do. If one thing goes wrong, we are at an even greater disadvantage than we already are.
Right now, us sitting here being able to do little more than walk around, we already are a sitting duck. Us sitting here and hoping we don't get creamed by an opponent that is orders of magnitude more fast than us is much more sitting duck like than using the one ability we have in this situation that can provide us with some maneuverability. You're assumning that rolling badly means we will fail, but there is only one roll where i foresee that happening, that's a one. With our plus 6 bonus the lowest we can roll except for insta-fail is an 8. That's not necessarily very good, but it's not necessarily instant failure either. If it flings us into the future only by a couple of minutes that's okay we can deal with that, but fighting a disadvantaged battle with opponents that would normally be considered our equal is just... dumb.
In comparison, you're suggesting we get into a confrontation that will inevitably lead to us using our worst possible skills.
Allow me to demonstrate with a simple dodge roll, something that would become inevitable in a confrontation.
1d20 -3 (untrained in combat) -2 (somewhat encumbered) vs 1d20 + (maybe four? let's be realistic guys, there's gonna be a bonus here)
that's a difference that's gonna be somewhere around nine, maybe more, though i doubt it's gonna be anything more than one less. So we can expect that in this situation we are 40-50% worse in any given melee combat situation in comparison to either of the unicorns.
All of your plans assume that the unicorn screws up at some point, which is much more likely on our end.
Note: Bringing up statistics may seem metagamey, but it's a good way to highlight our character's disadvantage, a disadvantage he likely feels now.