It bears looking at what exactly is being sanctioned. It is mentioned in the Wikipedia article you linked:
On 16 February 2015, the EU increased its sanction list to cover 151 individuals and 37 entities. Australia indicated that it would follow the EU in a new round of sanctions. If the EU sanctioned new Russian and Ukrainian entities then Australia would keep their sanctions in line with the EU.
This is the latest announcement concerning EU-imposed sanctions. There is an EU list of 151 individuals and 37 entities (mainly companies)
- who cannot enter (individuals) or do business with the EU,
- whose EU-based assets and accounts are frozen and cannot be accessed,
- with whom EU-based individuals and entities are forbidden to do business.
There’s a tiny bit more:
On 31 July 2014 the EU introduced the third round of sanctions which included an embargo on arms and related material, and embargo on dual-use goods and technology intended for military use or a military end user, a ban on imports of arms and related material, controls on export of equipment for the oil industry, and a restriction on the issuance of and trade in certain bonds, equity or similar financial instruments on a maturity greater than 90 days (In September 2014 lowered to 30 days)
On 18 December 2014, the EU banned some investments in Crimea, halting support for Russian Black Sea oil and gas exploration and stopping European companies from purchasing real estate or companies in Crimea, or offering tourism services.
On January 2018 the EU sanctioned entities who participated in the construction of the Crimea Bridge: Institute Giprostroymost, the firm which designed the bridge; Mostotrest, which has a contract to maintain the bridge; Zaliv Shipyard, which built a railroad line to the bridge; Stroygazmontazh Corporation, the main construction company that built the bridge; a subsidiary of Stroygazmontazh called Stroygazmontazh-Most and VAD, which built the roadway over the bridge, as well as access roads.
These were all individual occurrences of the search phrase EU, which is pretty much consistently used throughout the article in place of the long form or a placeholder. I cannot rule out the possibility of having missed something.
However, all things considered the sanctions only cover 37 entities on its main sanction list from 2015, an unenumerated number involved in the construction of the Crimea bridge and a couple of tightly defined business areas (military, oil production, financial stuff and stuff related to Crimea). This is far from the entire volume of trade Russia and the EU had. All other business areas are currently not restricted by European sanctions (although some might be by Russian countersanctions).
The lists and business areas are not set in stone. They can be amended or reduced by EU decisions at any point in time as the EU governments see fit. Thus, there is a potential danger of current investments being halted tomorrow—that risk has greatly reduced since 2015 (note that no new significant round of sanctions has been imposed since that was not tied to a specific event like the bridge building).
Businesses not on either sanction list and not operating in the sanctioned areas are of course free to conduct business in all legal ways they see fit.
Germany and France are two of the EU’s largest economies. Thus follows that they were affected by the sanctions most in absolute terms but also that investments from these countries in Russia can rise most in absolute terms when businesses no longer fear additional sanctions.