they bought many/most of their converts. They are popular amongst the gypsies
You may well be right to some extent, but:
1) It might be better to say "they bought many of their adherents": they are probably not so blind as not to realise they are not true converts.
2) My experience is mainly in Albania, never Romania, and it is true that many gypsies are drawn to western Evangelical and Pentecostal missionaries, and that their motive (as far as can be humanly discerned) is financial, but my conversations with missionaries tells me that this is a grief
to the missionaries, who are quite aware that they are sincerely preaching their message, and are attracting 'rice Christians'. Often they worry deeply about what to do to solve the problem - but meanwhile the adherents continue to come, and the missionaries do not turn them away.
3) The most successful, and well respected, admired work among gypsies which I visited in Albania is led by an American Negro. Many east European gypsies have very dark skin, and I think this brother's skin-colour has enabled him to penetrate the barrier of financial aspiration and reach some, perhaps many, of their hearts at a deeper level.
Gypsies and the 'white' population in Albania tend to operate an unofficial apartheid, and it is very difficult to get the two races to integrate, even in church life. The most successful I came across was a large church which had a well-loved and respected older man as one of the elders, who is also a gypsy.
Nonetheless, there may regrettably be some gullible or unscrupulous Evangelical missionaries who 'buy many of their converts'. As it is somewhere written, the Day will reveal it; I cannot say.