Yes.. although it is difficult to know if the issue is not going to continue with another brand.
I would do a wireless survey using a laptop or your phone.. just to see if it gets decent signal and speed in the location of your MacPro. Having the router well away from your office does seem a bit strange.. but anyhow.. what does the phone/laptop pickup in the same location?
A new card is unlikely to fix it.. and it is difficult to obtain the right cards for the slot.
https://www.tweaking4all.com/hardware/apple-computers/mac-pro-wifi-2008-2012/
Check the model card it has now.. and if the Cisco shows wireless signal at its end.. check how much signal you get.. wireless is always a two way dance.. strong signal from one side is not going to help if signal from the other is still poor.
Since you have the luxury of slots.. ah.. the bliss of slots. There are quite a number of excellent PC cards on the market.. i won't give URL to where they are listed.. because the naughty people there build their own Mac Pros.. out of.. shock horror.. PC parts.
Try a google search for Tony and Mac.. then look at the current buy list and wireless cards. TP-Link T9E or T8E for example should be fully Mac compatible.. but do check the forums.
There are occasionally USB wireless sticks that work. but seldom have good range.
There are two alternatives.
You can use Powerline Adapters.. (EOP or Homeplug in the US). These can work very well if the power cabling mets certain standards. Not multiple phase.. not breakers..
A set of AV1200 or AV2000 worked great for me during renovation when ethernet was cut.
This IMHO is much better than any wireless solution if you cannot run real ethernet. It is trial and error to see if it works.. so check the stores return policy.. but if they work .. they tend to work well without changing with temperature, wind speed, time of day, phase of the moon etc. As wireless is the least reliable form of networking anything with wires (almost) is preferred.
In the US they also sell MCoA which is same kind of thing for use over antenna cabling.. and some phone cabling ones are also available.
A wireless bridge.
Wireless routers have a number of variations.. WAP (wireless access point) and bridge which means wireless to ethernet.
That takes the wireless issue away from the Mac and makes it a separate box which can be located in a better spot in the room with the connection to the Mac by ethernet.
Suitable bridges must work with your main cisco router. Perhaps give us actual model number.
There are usually ones closely tied by brand.. like Apple routers can do wireless extend and bridge but only to another Apple router. Most brands do have some proprietary products for extending and bridging wireless.
There are also universal type repeaters and bridges. (most repeaters will work as a bridge).