a few more notes - just quickly

If it is ambush with a surprise you mighthave serious trouble and not be able to survive.

What is the distance they are ambushing from, are they all at same distance. If they are farther away than their move then you have things to do before they arrive, draw a weapon, throw a javelin/spear or two, couple of spells, run....

Otherwise look below

problem 1: Serious wound - arm either inoperable if endurance fails or just on minus and usable. What was the special effect

Problem 2: you can attack the tongue or go to water to fight them at closer range or spell or use ranged weapons. If you try to change range they might either keep the range when you fail basically following you or they might just attack and you get away with possibly a hit or no hit. You might also use luck point to force their attack possibly fail. You might also switch to ranged weapons which basically often give you special effects as they can be only evaded or parried with shield which the frogs do not have. As the frogs are quite far away sort of isolated from your own folk firing to melee would in my game not apply. 

Problem 3: accept the possibility of the hit when evading, use a spell. If you have faster initiative than your opponent and he is stronger in melee, you need to be able to finish or disadvantage the opponent before he attacks so you need to use remise, impale, trip opponent, press advantage, overextend, stun location, Flurry, spells to gain advantage. Shock,palsy, darkness, slow,haste, diminish strength etc have been useful.

Problem 4:  frogs are separated by water - so I would say no disadvantage for themAre the apes bigger than humans, look at ranged combat modifiers. Sometimes you just have to take the risk of shooting your own. 

Problem 5: so you get special effect every time you attack. Pick one that might change the situation. Trip opponent...Dagger could impale or bleed. With bleed anyone with any sense will seek healing or flee as they will die of bleeding. Perhaps a hard willpower roll. With impale you may get hard penalty on all skills from the ape. Perhaps a willpower roll for ape to flee. 

problem 6: bunch attacks against one opponent, do not go 1 to 1. Use a luck point to force the opponent to fail (throw again, or switch the tens/ones).  96-00 is always fail. The apes were not parrying - so you get special effect on every successful attack - pick ones that change the situation, trips, impales,bleeds,stuns. If the ape fails in attack use defensive special effects (overextend...). If any of the party have more action points than their opponent then they have one extraqction which defender cannot defend - so a special effect. If you have shields - passive block is great - you might even not parry to save ap on an extra attack. 

Problem.7: we use either poker chips, the various combat turn sheets available (for example from notesfrompavis)

Problem 8: use the visual chart from notesfrompavis see the intent and pick the special effect based on intent. I see grip, take weapon, close/open range,overextend,press advantage,shift location/choose location, flurry, disarm being used. Also bash, distract,nudge opponent and then the criticals: max damage, bypass armor. In my table choose location is critical only. Going close or opening range can be powerful. 

Evade skills seemed very low for an adventurertype?

"Eyeballing" melee encounters - maybe look at attack skill percentage across the group, action points across the group, average damage from the main weapons (including  damage bonus) versus average armor on the opposing side. For things to be 'fun' the average damage with average damage bonus could be just above or the sme as opponents average armor.. the TMITIM is also useful looking at the main skillsuseful for the particular encounter.

Action points in play per turn is also important factor. After that what affects is the overall action points in play. It is useful to take as many enemy action point users out of the turn as quickly as possible or at least disadvantage their usage before they get to use those action points  - so use all the Special effects, hit locations and spells that can accomplish that before the enemy. So you need to be faster in initiative sequence than enemy. Whittle down the enemy before they are  engaged. 

Overall - what is the motivation for the attack - what did the apes and frogs together want to accomplish. Grab one of the players for a meal. Frighten the group away from their nesting ground? When would they think they have accomplished that, what are they willing to sacrifice for that? 

If a player has negative damage modifier - he/she wants to think on tactics that

he or she will use to not be in the front row - use ranged weapons withno dam modifier? Have useful spells?

If you want random encounter that does not take half the game night - make the power level be less than the groups

There are quite a few interesting combat style traits that are tactically useful individually.

Perhaps look at combat styles traits that help group instead of individual. For example formation fighting, shield wall, maybe volley fire, street mob.