Difficulty of workouts

I have been between 4 and 4 1/2 stars for my fitness status for a few months, and I am now just a little bit over 4 stars (I tried to get a little rest before March, I am going to have a lot of time to ride in March and I have a race on April the 11th - the malteni ultra cx race).
Right now, the training advisor wants me to take hard trainings, as “there ain’t no way but the hard way” or higher ground 4, and I can’t finish them : I use them in Zwift, and after the first big interval I need to take power down, sometimes to 95% or to 90%, as the big power interval finish in the “erg spiral of death”.
What should I do? Should I try to lower the difficulty to 97% from the beginning?
I was in the base phase, with endurance training and this week I should get to climber trainings… my objective is gc specialist at the end (the malteni is a 250km cyclo-cross race with 20% road, 20% cobbles - French and Belgium-, 60% tracks, i did it in 12 hours last year and expect to be better this year… you have 5-8 minutes efforts in the cobbles or on high energy sections, then can rest a little bit).
Will climbers trainings be easier?

Any advice?

Try not using erg instead?

I tried disabling it but i imagine I should be able to finish the training, even with big difficulty… it seems I can go on very long putting good power but cannot put high power long enough.
I have (for 55kg) 233 tp, 732 pp, 189 ltp, and 17.6 hie. Is my hie too high?