The official statistics published by the European organisation Eurostat say this:
Proportion of minimum wage earners
The proportion of employees earning the minimum wage can vary considerably across countries. By linking microdata from the two latest four-yearly structure of earnings surveys (SES) with the level of minimum wages in force at the time (October 2010 and 2014), it is possible to derive an estimate of these proportions (as presented in Figure 4). For the sake of comparability, the scope has been restricted to full-time workers aged 21 years and over, working in enterprises with 10 employees and more, excluding public administration, defence and compulsory social security (NACE Rev. 2 Section O). Moreover, monthly earnings calculated from the SES exclude any earnings related to overtime and shift work.
In October 2014, the proportion of employees being paid less than 105 % of the national minimum wage was above 7.0 % in ten of the EU Member States that enforced a minimum wage, namely: Slovenia (19.1 %), Romania (15.7 %), Portugal (13.0 %), Poland (11.7 %), Bulgaria (8.8 %); France (8.4 %), Lithuania (8.1 %), Latvia (7.9 %), Greece (7.7 %) and Croatia (7.1 %). Belgium (0.4 %) recorded the lowest proportion of employees earning less than 105 % of the national minimum wage, while the proportion of employees in the remaining ten Member States earning less than this amount stood between 1.0 % (Spain) and 5.8 % (Luxembourg).
Development of the proportion of minimum wage earners
Between 2010 and 2014, the proportion of employees earning less than 105 % of the national minimum wage increased by more than 2.0 percentage points in Romania (11.7 points), Bulgaria (5.4 points), Poland (3.6 points) and Hungary (2.3 points), while it decreased by more than 2.0 points in Lithuania (-5.6 points) , Ireland (-5.1 points), Luxembourg (-4.1 points), Latvia (-4.0 points), Portugal (-3.8 points), Croatia (-2.6 points) and Slovakia (-2.2 points).
Eurostat, Statistics explained. From Minimum wage statistics Data extracted February 2018.
That would make this number quite high, although lower than compared to the original claim. However, the claim is about statistics and definitions. Those can change and are sometimes interpreted differently. This is crassly demonstrated when comparing unemployment rates for example. For example ILO definitions are completely different than what national statistics suggest.
The claim itself continues with
Now close to a third of the workforce receive the minimum wage - 1,846,498, if registered freelancers are included. “We are paid as if we were a country of unqualified workers,” complains the trade unionist. […]
Labour researchers believe over 40 per cent of workers in Romania are on the minimum wage, if unofficial jobs are factored into the figures. Meanwhile, the latest Government data shows that around 30 per cent of total contracts pay the national minimum wage or under. This is still a massive number, and contrasts with nine per cent in Germany.
From: How Romania sold out its workers to foreign investors for IMF and EU cash
That illusory precision number of "1,846,498" and "believe" seem in stark contrast. But as definitions vary, the following can also be hold "true":
Another important aspect is the share of employees affected by the minimum wage. As the ratio of the minimum wage to average wage grows, the minimum wage affects an increasing share of workers and its impact becomes larger. In Romania, in 2014, minimum wage affected 22% of employees, a larger proportion than in comparable countries like Poland and Lithuania (9%, in both) and Latvia (15%) IMF (2016).
Smaranda Pantea, Ministry of Public Finance: "Minimum wage hikes, impact on employment in Romania"
seems to be that: No, not according to official European statistics. And at the same time: Yes, going by the definitions labour researchers use that figure is probably in the right ball park.
How are these numbers counted? Who is included and why? Are all "workers" included or only those with official contracts, just employees or self-employed and freelancers as well? Are those contracts officially registered and paying out the right amount or only parts of that or are there jobs as part of the unofficial shadow economy? There are reasons to opt for one or the other definition, ranging from legitamate and well-argued for to manipulatively suggestive.
That may sound surprising and difficult to understand, but one such paper arguing in a similar direction reads:
According to a Romania Country Report (2015, p.20-21), “wage growth has been moderate but uneven, with the wage distribution becoming increasingly compressed at the bottom due to strong increases in minimum wages. It has been increasing sharply since 2012 and is expected to reach close to 48% of average gross earnings at the end of 2016.”
Approximately 2.4 million Romanian workers representing 40% of total active employees received the minimum wage or less in 2015. Of these workers, 1.6 million were full-time workers, and 0.8 million were part-time workers. If the wage achieves 46% of the gross average earnings, it will not have the capacity to guarantee the minimum standard of living for employees. A portion of these workers is paid at the minimum wage or less to avoid a tax payment to authorities.
Adriana Anamaria Davidescu & Friedrich Schneider: "Nature of the Relationship between Minimum Wage and the Shadow Economy Size:
An Empirical Analysis for the Case of Romania", IZA DP No. 11247, 2017.