There is only a small difference between Swiss and English.

I've forced an English BB into well-greased Swiss threads, had to work the cups in with much back-and-forth action from a big wrench on a splined cup tool on both sides, but it finally bottomed in reassuringly.
I backed off 1/4 turn for every 1/2 turn advanced. Fairly physical work, this.
Saved me a big headache but took about ten minutes each side, working carefully to prevent the tool from slipping and damaging the splines in the cup.
It might be best to secure the wrench/tool using a bolt into (and/or thru) the bb spindle to keep anything from slipping, but in my case I just pushed in against the wrench and tool and applied precise motion as well as I could.

Depending how long is the threaded portion of the cups, will determine how much thread interference results from the slight pitch variation.

I was able to thread in the English bb cups a couple of turns before any interference resistance was felt.

To apply force to the adjustable cup means that the cup must not be turned with just a pin spanner, it would break the pins I'm sure, but once I worked in the splined cups they can now also be removed without tremendous force. I put in a Shimano cartridge bb so will likely never have to replace it.