From the viewpoint of the guilds Falma is the villain, and while I wouldn't necessarily say he's evil he could be viewed as an antagonist in this situation.
He's utilizing knowledge from another world with more advanced medical techniques, techniques unavailable to other medical professionals.
His sales and marketing techniques are also based on future practices which have had significantly more study put behind them.
He's selling medicines drastically under market value, causing a drastic shift in costs which other businesses cannot afford.
By virtue of how he's been taking the customers of others using these tactics, other pharmacies are risking losing their own stores.
He's now established a guild, which in it's own way is the same tactic the guild has been using up to this point.
While yes for Falma he's using these for the good of others, we see this as the observer. To the Pharmacy guild though who don't realize his intentions he's definitely a villain come to ruin them all and take all the business for himself. This is why Pierre is such an important character to begin interaction with Falma as it begins to help spread his intentions. This of course can STILL be viewed as antagonistic in it's own way as now people have to join his Dispensary guild to get his techniques and recipes. Don't get me wrong, the idea of medicine that works and isn't a poison is good and all, but there's been no opportunity to clearly demonstrate this for the Pharmacy guild. A lot of this is attributed to the Pharmacy guild not giving Falma the time of day, true. But what efforts has Falma made to talk to them? With the backing he has he could make a greater effort to breach this issue with them.
But in the end it's just my opinion about this enjoyable story!