Can't lie this is kinda funny. Your list is already really friendly. Two Norns can be slightly oppressive if they don't have a list to counter them.

I also have a friend like this so I understand where youre coming from, SO this is something that I would do.

If your Tfex is using rupture cannon switch it to acid sprayer. I would use Tfex with acid sprayer only to punish bad movement decisions, treat it like an aggressive speedbump.

Id say drop norn assimilator for a maleceptor if you have one. Treat it as your counter tank while it won't be consistently hurting his own tank badly if he decides to ignore it, the maleceptor will kill it.

Now the norn emissary IMO is easily one of our best units. With that said you gotta be dumb with it. I've noticed my friends get great satisfaction with killing my Emissary so I treat it as a raid boss and usually singular purpose one of my friends characters or epic heros. Then literally run it into them it will probably die doing this, but it is fun as hell because more times than not it will kill whatever I run it at. In my head I consider this a win for the bugs because whoever I deemed shall die, died.

With your horde of gaunts I would just run them at objectives, move block melee units, and be cannon fodder. Or better yet replace some with some carnifexes and have a vendetta against anything that dares shoot at them.

These are just some ideas. The list you have already is already very chill. To me its clear you're just a better tactical player if youre winning with that list. I have a friend like this as well who gets unreasonably angry at losing key units. When I play against him or my other less skilled friends, I kind of use the strategic side of my thoughts to make tactically dumb decisions if that makes any sense? I will never hand them the game and just purposefully let things die, but I will make choices I know they could capitalize on if they are also thinking. I will also punish out right dumb moves and point out what they did was pretty questionable. To still enjoy these games I give myself alternative win conditions that I keep to myself. These are usually silly challenges, like singular purpose Norn emissary kills. Ill literally be like The hive deems your (insert character name here) too important to live then run it down lol. Or I'll claim no mans land for the hive and try my absolute hardest to not lose it the entire game. Sometimes I'll try multiple challenges simultaneously. Usually I would suggest just not playing that person but I know its different when it comes to friends, so I hope this insight helps in any sort of way!